CONTROL OF PROBLEM WEEDS
Bob Parker
Revised October 24, 2008

This section gives information about specific weeds that may be troublesome to control. Herbicides and/or rates listed cannot necessarily be used on cropland. Rates of application and restrictions vary depending on crop or site. Do not apply to a crop or site not listed on the label.
Noncropland is where plants grow that are not harvested by humans or animals for food, feed, or fiber― roadsides, for example.  
Highly volatile esters of 2,4-D are not permitted. Low-volatile (LV) esters are restricted in some parts of Washington.
Caution  This handbook is not intended to be a complete guide to herbicide use. Before using any chemical, you should read the label recommendations on the container. Before a chemical can be recommended for a specific use, it must be thoroughly tested. Following the recommendation on the manufacturer’s label can prevent many problems arising from the wrong use of a chemical.
probwd  Beancaper, Syrian (Zygophylium fabago) 
Remarks  Control is unknown, although metsulfuron appears promising in initial trials. Other data suggest that both glyphosate at 1.5 lb ae/A and picloram at 1 lb ae/A are effective. 
Site of action  (metsulfuron) Group 2: acetolactate synthase (ALS) inhibitor; (glyphosate) Group 9: inhibits EPSP synthase; (picloram) Group 4: synthetic auxin 
Chemical family  (metsulfuron) sulfonylurea; (glyphosate) none generally accepted; (picloram) phenoxy acetic acid
probwd   Bermudagrass (Cynodon dactylon) 
•  glyphosate
Rate  3.75 lb ae/A
Time  Apply to actively growing bermudagrass with seed heads.
Remarks  Retreatment may be necessary. Rain within 6 hr after application may reduce effectiveness. Allow at least 7 days after application before tillage.
Caution  Glyphosate is nonselective; spray will injure or kill vegetation contacted.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted.
•  fluazifop (Fusilade DX)
Rate  0.25 to 0.375 lb ai/A (1 to 1.5 pints/A)
Time  Apply to actively growing bermudagrass with 4- to 8-inch runners.
Remarks  Apply with 1% (v/v) crop oil concentrate or 0.25% (v/v) nonionic surfactant. Acts very slowly, taking at least 2 wk and often 4 wk to show effectiveness. Do not apply to stressed grasses. If weeds regrow, reapply at 0.1875 to 0.375 lb ai/A.
Caution  Do not use crop oil concentrate if treating bermudagrass in ornamentals. Do not apply if rain is expected within 1 hr.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
probwd Bindweed, field or perennial morningglory (Convolvulus arvensis)  
•  dicamba (Banvel, Rifle, or Clarity) or 
•  dicamba  +
•  2,4-D (for suppression)
Rate  0.5 to 1 lb ae/A dicamba; or 0.5 to 1 lb ae/A dicamba + 1 to 2 lb ae/A  2,4-D
Time  Apply during fallow before planting and when weeds are actively growing.
Remarks  Rates are to suppress field bindweed.
Caution  Refer to label for crop rotation restrictions. Avoid drift to sensitive crops.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (dicamba) benzoic acid; (2,4-D) phenoxy acetic acid
•  dicamba (Banvel, Rifle, or Clarity) or
•  dicamba  +
•  2,4-D (for control)
Rate  1 to 2 lb ae/A dicamba; or 1 to 2 lb ae/A dicamba + 1 to 2 lb ae/A  2,4-D
Time  Apply in late summer or fall before killing frost.
Remarks  Control is best when weeds are actively growing and in postbloom stage. Make follow-up application in spring to control seedlings.
Caution  See label for in-crop use and rotation restrictions. Avoid drift to sensitive crops.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (dicamba) benzoic acid; (2,4-D) phenoxy acetic acid
•  picloram (Tordon)
Rate  1 lb ae/A
Time  Apply in the growing season on noncropland when bindweed is visible. Timing is not critical, but results are most consistent if bindweed is in early bud to full bloom.
Remarks  Apply as a coarse, low-pressure spray in sufficient volume to cover adequately. For control in fallow, refer to Winter Wheat—Nonirrigated East of Cascades in this Handbook.
Caution  A restricted-use herbicide. Picloram is registered only on rangeland and permanent pastures and on fallow grainland east of the Cascades. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to picloram. Do not plant these crops until an adequately sensitive bioassay or chemical test shows that no picloram is detectable in the soil. Extend treatment 10 ft beyond the infestation. Do not use in diversified cropping areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  glyphosate
Rate  3 to 3.75 lb ae/A
Time  Apply at full bloom to early seed stage of maturity. Application on fall regrowth may provide some control.
Remarks  Cover foliage thoroughly but avoid spray runoff. Retreatments may be needed for complete control. Control improves if the treated area is tilled 2 to 3 wk after treatment.
Caution  Glyphosate controls grasses as well as other vegetation in treated areas.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  metsulfuron (Escort)
Rate  0.6 to 1.2 oz ai/A (1 to 2 oz/A)
Time  Apply to actively growing bindweed in bloom stage.
Remarks  Treatment is suppressive. Use a nonionic or silicone surfactant to improve control.
Caution  Do not allow spray drift to sensitive crops. This rate is only for noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  2,4-D amine
Rate  Broadcast treatment: 2 to 3 lb ae/A
Time  Apply at bud growth stage or at summer fallow in early August.
Remarks  Use 2,4-D to help reduce bindweed stand 60 to 80% and prevent seedling establishment. It is important to apply 2,4-D every year; skipping an application gives bindweed a chance to recover. During the grain year, apply 2,4-D to growing winter wheat. After wheat matures, apply 2,4-D with a sprayer mounted on the combine, or apply after combining.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  glyphosate  +
•  dicamba (Banvel, Rifle, or Clarity)
Rate  1.5 lb ae/A glyphosate + 0.5 lb ae/A dicamba
Time  Apply mid- to late bloom but before seed matures. Applying to fall regrowth may give some control.
Remarks  Use this tank-mix during summer fallow before planting small grains.
Caution  Crop may be somewhat injured if dicamba is applied within 45 days of planting. Glyphosate controls grasses as well as other vegetation in treated areas.
Site of action  (glyphosate) Group 9: inhibits EPSP synthase; (2,4-D) Group 4: synthetic auxin
Chemical family  (glyphosate) none generally accepted; (dicamba) benzoic acid
•  glyphosate + 2,4-D (Landmaster BW)
Rate  0.378 to 0.67 lb ae/A (54 oz/A Landmaster)
Time  Apply in fallow or postharvest to bindweed runners at least 10 inches long. Use 1% solution to spot treat with high-volume, spray-to-wet applications. Tilling after treatment may improve control.
Remarks  In fallow, cultivate until July 1; then allow weeds to grow to treatment stage.
Caution  Avoid drift to sensitive crops.
Site of action  (glyphosate) Group 9: inhibits EPSP synthase; (2,4-D) Group 4: synthetic auxin
Chemical family  (glyphosate) none generally accepted; (2,4-D) phenoxy acetic acid
•  quinclorac (Paramount)
Rate  6 oz ai/A (8 oz/A)
Time  Apply in fall before frost to actively growing bindweed with stems at least 4 inches long.
Remarks  Must add methylated seed oil at 1 to 2 pints/A or crop oil concentrate at 2 pints/A. Plant uptake is through both foliage and roots. Rain after application is important for soil uptake.
Caution  Note crop rotation restrictions before using. Do not exceed 12 oz ai/A per calendar year.
Site of action  Group 4: synthetic auxin
Chemical family  Quinoline carboxylic acid
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb ai/A
Time  Apply after 25% bloom through fall to actively growing bindweed.
Remarks  Add 1 quart/A methylated seed oil.
Caution  Note crop rotation restrictions before using.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd  Blackberry vines, wild (Rubus spp.) 
•  picloram (Tordon)
Rate  1 lb ae with 50 gal of water for spot treatment sprays
Time  Apply in late spring after leaves are fully developed.
Remarks  Foliage must be thoroughly wet. Reapplication will be required as regrowth occurs.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to picloram. Do not use picloram in diversified cropping areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  glyphosate
Rate  Broadcast—use 2.25 to 3 lb ae/A. Spot treat—use 1% to 1.5% solutions.
Time  Apply in September to October when canes are actively growing and after berries are formed. Fall treatments must be before a killing frost.
Remarks  Fall spray treatment symptoms may not show before frost. Retreatment may be necessary for complete control. Trailing blackberry is more difficult to control.
Caution  Glyphosate controls grasses in the treated area as well as other vegetation.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  metsulfuron (Escort and others)
Rate  Escort: 0.3 to 0.6 oz ai/A (0.5 to 1 oz/A) 
Time  Apply to fully leafed-out vegetation before fall leaf coloration.
Remarks  Constantly agitate while mixing product in water. Add 0.25% by volume of nonionic or silicone surfactant to spray mixture. Good coverage is essential. Application sites differ between products; consult labels.
Caution  Avoid contacting sensitive crops. Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  triclopyr ester (Garlon 4) or
•  triclopyr amine (Garlon 3A) or
•  triclopyr + 2,4-D (Crossbow)
Rate  Spot treatment—mix 3 lb ae Garlon 4 or 3.75 lb ae Garlon 3A with 100 gal water, or 1 pint Crossbow in 12 gal water. Broadcast—use 1 to 4 lb ae/A Garlon 4 or 1.5 to 4.5 lb ae/A Garlon 3A or 1 to 2 gal/A Crossbow.
Time  Apply when plants are actively growing. For dormant application, mix Garlon 4 in diesel oil or in water with 3% of an oil substitute.
Remarks  Foliage must be thoroughly wet.
Caution  Use on rights-of-way, industrial sites, and for forestry (release and site preparation). Crossbow can be used on permanent pasture and rangeland, up to 1.5 lb ae/A. Observe all grazing and harvesting restrictions.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (triclopyr) pyridine; (2,4-D) phenoxy acetic acid
probwd  Blueweed, Texas (Helianthus ciliaris) 
•  dicamba (Banvel, Rifle, or Clarity)
Rate  2 to 4 lb ae/A
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  imazapyr (Arsenal)
Rate  1 lb ae/A
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  clopyralid (Stinger or Transline) or
•  glyphosate or 
•  MCPA (various products) or
•  picloram (Tordon) or
•  2,4-D (various trade names)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  (clopyralid, MCPA, 2,4-D, and picloram) Group 4: synthetic auxin; (glyphosate) Group 9: inhibits EPSP synthase
Chemical family  (clopyralid and picloram) pyridine; (glyphosate) none generally accepted; (MCPA and 2,4-D) phenoxy acetic acid
probwd  Brackenfern, western (Pteridium aquilinum) 
•  asulam (Asulox)
Rate  1.6 to 3.3 lb ai/A
Time  When bracken is in full frond.
Remarks  Apply on uncultivated land, reforestation sites, and Christmas tree plantations only. Asulam has a half-life of 6 to 14 days in soil.
Caution  See label for precautions.
Site of action  Group 18: inhibits DHP synthase step
Chemical family  Carbamate
•  dicamba (Banvel, Rifle, or Clarity)
Rate  4 to 8 lb ae/A
Time  Apply in late winter before fronds emerge.
Remarks  Management for maximum crop competition aids control. Will not control grasses.
Caution  Avoid drift to sensitive crops. Clover stands may be reduced or eliminated in pastures.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  glyphosate
Rate  2.25 to 3 lb ae/A or a 1 to 1.5% solution when using hand-held equipment
Time  When bracken fronds are at least 18 inches long.
Remarks  Adequate foliar coverage is necessary.
Caution  Glyphosate controls grasses in the treated area as well as other vegetation.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
probwd  Broom, Scotch (Cytisus scoparius) 
•  glyphosate
Rate  1.5 to 3 lb ae/A or 1.5 to 2% solution for handgun application
Time  Apply to actively growing plants in the spring.
Remarks  See Forestry section of this handbook for information on control in conifers. Adding a recommended surfactant improves results.
Caution  Also controls grasses and other plants needed to compete with Scotch broom seedlings.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  triclopyr ester (Garlon 4) or
•  triclopyr amine (Garlon 3A) or
•  triclopyr + 2,4-D LV ester (Crossbow)
Rate  0.5 to 1.5% concentration of Garlon 4 or Crossbow, or 1 to 1.5% concentration of Garlon 3A
Time  Apply any time the plants are actively growing. Garlon 4 and Crossbow can be used for basal bark applications any time of year.
Remarks  Foliage must be thoroughly wet. For Garlon 3A, it is especially important to use a high volume of water (100 gal/A or more).
Caution  Garlon products are registered for use on rights-of-way, industrial sites, and forestry (release and site preparation). Crossbow can be used on permanent pastures and rangeland up to 1.5 lb ae/A. Observe all grazing and harvesting restrictions.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (triclopyr) pyridine; (2,4-D) phenoxy acetic acid
probwd  Buffalobur (Solanum rostratum) 
•  glyphosate  or
•  clopyralid (Stinger or Transline)  or
•  picloram (Tordon)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  (glyphosate) Group 9: inhibits EPSP synthase; (clopyralid and picloram) Group 4: synthetic auxin
Chemical family  (glyphosate) none generally accepted; (clopyralid and picloram) pyridine
probwd  Bulrush, small-fruited (Scirpus microcarpus)  and softstem (Scirpus validus)  
•  2,4-D LV ester 
Rate  3 lb ae of 2,4-D ester in 100 gal water. Use LV ester formulation plus 3 gal diesel or stove oil for spot treatment.
Time  Apply to growing plants. Respraying is necessary for complete control.
Remarks  Foliage must be thoroughly wet.
Caution  Avoid drift to sensitive crops and desirable vegetation.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
probwd Burdock, common (Arctium minus) 
•  2,4-D LV ester or 
•  2,4-D amine
Rate  2 lb ae/A
Time  Before flower buds develop.
Remarks  Plants should be actively growing at time of treatment.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  triclopyr + clopyralid (Redeem R&P)
Rate  1.5 to 2 pints/A
Time  Apply when weeds are actively growing.
Remarks  Add a nonionic surfactant at the surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Avoid drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  aminopyralid (Milestone)
Rate  1 to 1.5 oz ae/A (4 to 6 fl oz/A Milestone)
Time  Apply to actively growing plants in the rosette.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. 
Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Bursage, skeletonleaf (Ambrosia tomentosa) 
•  2,4-D
Rate  1.5 to 2 lb ae/A
Time  Apply after tilling 3 to 4 inches deep and when regrowth is 4 to 6 inches tall.
Remarks  If not tilled, treat in spring and fall. Two to three annual retreatments may be needed for complete control.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  picloram (Tordon)
Rate  1 lb ae/A
Time  Apply when plants are fully leaved and actively growing.
Caution  Most formulations are restricted-use herbicides. See label for grazing restrictions. Do not contaminate water. Potatoes, beans, and many other crops are very sensitive to picloram. Do not use in diversified cropping areas. At rates above 0.5 lb ae/A (1 quart/A), apply only as spot treatment not to exceed 25% of a landowner’s acreage in a given watershed in a single season.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Bursage, woolyleaf (Ambrosia grayi) 
•  dicamba (Banvel, Rifle, or Clarity)
Rate  2 to 4 lb ae/A
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  imazapyr (Arsenal)
Rate  1 lb ae/A
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Buttercup, creeping (Ranunculus repens) 
•  MCPA LV ester  or 
•  MCPA amine
Rate  1.5 lb ae/A
Time  Apply when the buttercup is growing well.
Remarks  Avoid drift to sensitive crops and desirable vegetation.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
probwd Canarygrass, reed (Phalaris arundinacea) 
•  glyphosate
Rate  1.2 to 2.25 lb ae/A
Time  Apply to actively growing plants at early heading or in fall from mid-September to after first light frost.
Remarks  Check label regarding using a surfactant.
Caution  Glyphosate controls other vegetation in the treated area.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  sulfometuron (Oust)
Rate  2.25 to 3.75 ai/A (3 to 5 oz/A)
Time  Preemergence to early postemergence.
Remarks  Recommended for use on noncropland only. Do not apply to frozen ground. Constantly agitate while mixing in spray solution. Add 0.25% v/v nonionic surfactant to increase activity of postemergence applications. Apply with ground equipment in at least 15 gal/A carrier.
Caution  Keep sulfometuron out of cropland. Use equipment dedicated to noncropland uses only. Do not treat powdery, dry soils or light, sandy soils if rain is not likely after treatment.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  fluazifop (Fusilade DX)
Rate  0.25 to 0.375 lb ai/A (1 to 1.5 pints/A)
Time  Apply to actively growing reed canarygrass.
Remarks  Apply with 1% v/v crop oil concentrate or 0.25% v/v nonionic surfactant. Acts very slowly, taking at least 2 wk and often 4 wk to show effectiveness. Do not apply to stressed grasses. If weed regrows, repeat application.
Caution  Do not use crop oil concentrate if treating reed canary-grass in ornamentals. Do not apply if rain is expected within 1 hr.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
  imazapyr (Habitat or Arsenal)
Rate  0.5 to 1 lb ae/A
Time  Apply in boot stage through fall, when plant is actively growing.
Remarks  Habitat is labeled for aquatic sites. Arsenal is labeled for rangeland, pasture and noncropland use only. Always add the appropriate surfactant.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Carrot, wild or Queen Anne’s lace (Daucus carota)  
•  MCPA
Rate  1 lb ae/A
Time  Apply in spring or fall when wild carrot is actively growing but before bolting.
Remarks  Seedlings are easier to control than older plants. Treat annually to control seedlings.
Caution  Avoid spray drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A of the 75% Telar)
Time  Apply early postemergence to actively growing plants.
Remarks  Using a nonionic surfactant increases effectiveness.
Caution  Apply only to pasture, range, Conservation Reserve Program (CRP), and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  metsulfuron (Ally and others)
Rate  Ally: 0.12 to 0.18 oz ai/A (0.2 to 0.3 oz/A)
Time  Apply early postemergence to actively growing plants.
Remarks  Using a nonionic or silicone surfactant increases effectiveness.
Caution  Consult labels for crops on which each product can be used.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Cattail, common (Typha latifolia and related species) 
•  2,4-D ester
Rate  6 lb ae per 100 gal of spray solution for spot treatments. Add crop oil, diesel oil, or surfactant to increase wetting.
Time  Apply before cattail heads appear in spring.
Remarks  Foliage must be thoroughly wet. 2,4-D does not control as well as glyphosate but is less expensive. 2,4-D must be reapplied to give satisfactory control.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  glyphosate
Rate  3 lb ae/A
Time  Apply to mature cattails after heads are formed and before frost.
Remarks  Allow 7 days or longer before clipping or tillage operations. Use additional surfactant.
Caution  Glyphosate controls grasses as well as other vegetation in treated areas.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
  imazapyr (Habitat)
Rate  0.5 to 1 lb ae/A
Time  Apply after cattail head appears in the boot or after head emerges and before killing frost.
Remarks  Add suitable adjuvant to spray solution.
Caution  Do not apply in the root zone of desirable trees. Treated water cannot be used for irrigation for 120 days.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Chervil, wild (Anthriscus sylvestris) 
•  glyphosate
Rate  2.25 lb ae/A 
Time  Apply to actively growing plants from bud to early flower.
Remarks  Glyphosate is nonselective and will kill or injure vegetation that might compete with new chervil seedlings.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  imazapyr (Arsenal)
Rate  0.75 lb ai/A 
Time  Apply to actively growing plants from bud to early flower.
Remarks  Add an appropriate surfactant
Caution  Use on rangeland, pasture, and noncropland only.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Comfrey (Symphytum officinale) 
Comfrey was a food and feed crop but has become weedy in gardens and fields of the Pacific Northwest. Naturally aggressive spread is accelerated by tillage that moves plant parts. A 1970s experiment in western Oregon determined the activity of several herbicides on comfrey. Relatively high rates were used, but only a few herbicides were effective. Most problems with comfrey are in gardens, so use caution in recommending any herbicide. One of the few options is to repeatedly (about every 3 wk) remove plants down as far as practical below the soil surface.
Herbicides that gave good control were bromacil and terbacil at 6 lb ai/A; picloram at 1 lb ae/A; 2,4-D ester at 2 lb ae/A; triclopyr at 2 lb ae/A; and clopyralid at 4 lb ae/A. These rates gave nearly complete control of a new planting. Older plants might be more difficult to control. 
probwd Cordgrass (Spartina spp.) 
•  glyphosate (Rodeo)
Rate  2 to 3.75 lb ae/A broadcast, 2% to 5% solution through hand-held equipment, or 33% solution with wiper applicators
Time  Apply to actively growing cordgrass any time from late June until first killing frost.
Remarks  Treat at least 6 hours before tidewater will cover plants. Debris and silt on cordgrass reduce performance. It may be necessary to wash plants before application. Add approved nonionic surfactant at 1 to 2 quarts/100 gal spray mix or 10% by volume with wiper applicators.
Caution  With hand-held equipment, do not spray to point of runoff.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  imazapyr (Habitat)
Rate  1 to 1.5 lb ae/A
Time  Apply to actively growing cordgrass, usually mid-June until killing frost. 
Remarks  Add suitable adjuvant to spray solution.
Caution  Do not apply in the root zone of desirable trees. Treated water cannot be used for irrigation for 120 days.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Crazyweed (Oxytropis spp.) 
•  picloram (Tordon)
Rate  0.25 lb ae/A
Time  Apply from early bud to bloom. Plants should be actively growing at the time of application.
Remarks  Plants are poisonous to livestock. To be used on rangeland or permanent grass pastures.
Caution  Most formulations are restricted-use herbicides. Do not graze until plants dry up after application. Avoid drift to sensitive crops. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to these herbicides. Do not use picloram in diversified crop areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  metsulfuron (Escort and others)
Rate  Escort—0.3 oz ai/A (0.5 oz/A)
Time  Apply to actively growing plants.
Remarks  Using a nonionic or silicone surfactant increases effectiveness. Application sites differ between products, see label.
Caution Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Cress, hoary or whitetop (Cardaria draba and related species)  
•  2,4-D LV ester or 
•  2,4-D amine
Rate  2 to 3 lb ae/A in noncropland and 1 lb ae/A as a selective treatment
Time  Apply early in cress growth stage; control is minor after bud stage. In cereals, apply 2,4-D before weeds reach boot stage.
Remarks  When possible, use 2,4-D on whitetop plants before plowing fields in spring. Respray in fall if new growth appears.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb/A
Time  Apply after blossoms open (full bloom) until plants desiccate. Fall rosettes also may be treated.
Remarks  Add 1 quart/A methylated seed oil. 
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A of 75% ai Telar)
Time  Apply at prebloom to bloom growth stage or to rosettes in fall.
Remarks  Using an 80% ai surfactant increases effectiveness.
Caution  Apply only to pasture, range, Conservation Reserve Program (CRP), and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  metsulfuron (Escort and others)
Rate  Escort—0.6 oz ai/A (1 oz/A) of the 60% ai
Time  Apply at prebloom to bloom growth stage or to rosettes in fall.
Remarks  Using a nonionic or silicone surfactant increases effectiveness. Application sites differ between products; consult label.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Cucumber, wild (Marah oreganus) 
Wild cucumber is a perennial vine that regrows each year from an enormous root. The plant spreads by seed, not by root fragments. The harmful effect of wild cucumber is mostly a result of the top growth that crowds, shades, and deforms the crops. Any type of physical control has temporary results because of the food storage in the root. This food reserve also means that if herbicides are to be effective, they must move to the root and block production of new shoots. Any control plan should call for treatment for several years. Recommendations that follow are based on limited research at Oregon State University. 
•  glyphosate
Rate  1.5 lb ae/A or 0.5 to 1% solution for application with a handgun
Time  Apply when the cucumber is growing rapidly in late spring or early summer.
Remarks  In two experiments, plants treated with glyphosate had no regrowth 1 yr later.
Caution  Glyphosate is a nonselective herbicide.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  picloram (Tordon)
Rate  0.5 lb ae/A or 0.5% concentration for application with a handgun
Time  Apply when cucumber is growing rapidly in the late spring or early summer.
Remarks  Expect 80 to 100% control 1 yr after treatment.
Caution  Most formulations are restricted-use herbicides.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  dicamba (Banvel, Rifle, or Clarity)
Rate  1 to 2 lb ae/A or 1% concentration for application with a handgun
Time  Apply when cucumber is growing rapidly in late spring or early summer.
Remarks  Expect 80 to 100% control 1 yr after treatment.
Caution  Dicamba seriously reduces seed production of grasses or grain crops if applied at the wrong growth stage. Do not use 2-lb rate on large areas if a crop is growing in the field.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  triclopyr (Garlon)
Rate  1 lb ae/A or 0.5% concentration for application with a handgun
Time  Apply when cucumber is growing rapidly in late spring or early summer.
Remarks  Tests with the ester form had excellent results 1 yr later. At 0.5 lb ae/A, results were less clear, but two of three plots had good results.
Caution  See label for registered sites for triclopyr products’ use.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  triclopyr + 2,4-D (Crossbow)
Rate  0.5 lb + 1 lb ae/A (2 quarts/A Crossbow) or 1% concentration for handgun application
Time  Apply when cucumber is growing rapidly in late spring or early summer.
Remarks  In two of three plots, results were good 1 yr after treatment. Results were poor in the third plot.
Caution  Check the Crossbow label to determine registered sites and rates.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (triclopyr) pyridine; (2,4-D) phenoxy acetic acid
probwd Devil’s-claw (Proboscidea louisiana) 
•  2,4-D (various products)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
probwd Dock (Rumex spp.) 
•  2,4-D or
•  dicamba (Banvel, Rifle, or Clarity) or
•  picloram (Tordon)
Rate  A mixture of each product 1 lb ae/50 gal of water for spot treatments
Time  Apply before flower elongation.
Remarks  Repeated treatments needed to control regrowth. Dicamba is effective on curly dock (Rumex crispus) but not on broadleaf dock (R. obtusifolius). Picloram is effective on both species and is registered for use on grazing and noncropland.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to these herbicides. Do not use picloram in diversified crop areas.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (2,4-D) phenoxy acetic acid; (dicamba) benzoic acid; (picloram) pyridine
•  aminopyralid (Milestone) 
Rate  1 to 1.5 oz ae/A (4 to 6 fl oz/A Milestone)
Time  Apply to actively growing plants before the bud stage of growth.
Remarks  A nonionic surfactant at 1 to 2 quarts/100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not let spray drift onto desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed.  Do not exceed 7 fl oz/A Milestone per yr.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A)
Time  Apply to young, actively growing weeds.
Remarks  Do not apply to frozen ground. Constantly agitate while mixing in spray solution. Add 0.25% v/v nonionic surfactant to the spray mixture. Apply with ground equipment in at least 10 gal/A carrier.
Caution  Avoid contact with sensitive crops. Labeled for pasture, range, Conservation Reserve Program (CRP), and noncropland use only. Do not treat powdery, dry soils or light, sandy soils if rain is not likely after treatment.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  metsulfuron (Ally and others)
Rate  Ally: 0.06 to 0.12 oz ai/A (0.1 to 0.2 oz/A)
Time  Apply to young, actively growing weeds.
Remarks  Do not apply to frozen ground. Constantly agitate while mixing in spray solution. Add 0.25% v/v nonionic or silicone surfactant to the spray mixture.
Caution  Avoid contacting sensitive crops. Consult labels for crops on which each product can be used. Do not treat powdery, dry soils or light, sandy soils if rain is not likely after treatment.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  sulfometuron (Oust)
Rate  2.25 oz ai/A (3 oz/A)
Time  Apply preemergence to early postemergence.
Remarks  Recommended for use on noncropland only. Rate depends on annual rainfall. Do not apply to frozen ground. Constantly agitate while mixing in spray solution. Add 0.25% v/v nonionic surfactant to increase activity of postemergence applications. Apply with ground equipment in at least 15 gal/A carrier.
Caution  Keep sulfometuron methyl out of cropland. Equipment used to apply this material should be dedicated to noncropland uses only. Do not treat powdery, dry soils or light, sandy soils if rain is not likely after treatment.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  glyphosate
Rate  2.25 to 3.75 lb ae/A
Time  Apply at early heading.
Remarks  Glyphosate is a foliar-active herbicide.
Caution  Glyphosate controls grasses as well as other vegetation in treated areas.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  2,4-DB amine or
•  2,4-D ester (Butyrac or Butoxone)
Rate  1 to 1.5 lb ae/A
Time  Apply before flower stalk elongates. Repeated applications are necessary.
Remarks  This treatment is selective on legumes and grass crops.
Caution  Spray 30 days before feeding forage. Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
probwd Dodder (Cuscuta spp.) —in forage alfalfa
•  pendimethalin (Prowl H2O)
Rate  1.9 to 3.8 lb ai/A
Time  Apply to dormant, established alfalfa before dodder germinates.
Remarks  Besides dodder, treatment controls most annual grasses and certain broadleaf weeds as they germinate. Controls most annual grasses and several broadleaf weeds, including dodder, as they germinate. Incorporation with rain or sprinkler irrigation enhances control. Will not control emerged weeds.
Caution  Do not apply to seedling alfalfa. Preharvest interval is 50 days for hay or forage. Do not exceed 4 quarts/A product per year. Refer to label for crop rotation restrictions.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
probwd Dodder (Cuscuta spp.)—general infestations in seed alfalfa fields
•  pendimethalin (Prowl, Prowl H2O, Stealth)
alfalfa for seed only
Rate  2 to 4 lb ai/A
Time  Apply to established alfalfa between January 15 and April 30 but before dodder germinates.
Remarks  Active special local needs labels include ID-930012, OR-000030A and OR-000030B for Prowl 3.3; OR-070027 for Stealth; and ID-060006, OR-060005 and WA-070002 for Prowl H2O. Besides dodder, treatment controls most annual grasses and certain broadleaf weeds as they germinate. Processed seed must be labeled “Not for human or animal consumption” at the processing plant, and all seed screenings must be disposed of in a way that they cannot be distributed or used for food or feed.
Caution  Use only on alfalfa grown for seed. Do not apply to seedling alfalfa. Do not graze or harvest alfalfa for hay after application. Do not use screenings from seed processing as feed for livestock. Do not use harvested seed for sprouting.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  pronamide (Kerb)
Rate  1 to 2 lb ai/A. Apply 1.5 to 2 lb ai/A in furrow-irrigated or rill-irrigated fields and 1 to 1.5 lb ai/A in flood-irrigated fields.
Time  Apply in spring before dodder germinates. On furrow-irrigated fields, follow a shallow incorporation by irrigation within 7 days. On flood-irrigated fields, follow application by flooding within 1 to 3 days.
Remarks Field treatment seldom controls dodder 100%. Scout fields for dodder patches and spot treated them.
Caution  A restricted-use herbicide. Pronamide controls grasses in alfalfa fields.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Benzamide
probwd Dodder (Cuscuta spp.)—general infestations in carrot seed fields
•  pendimethalin (Prowl)
carrots for seed only
Rate  0.5 to 2 lb ai/A
Time  Apply after the last normal cultivation (layby) as a directed spray.
Remarks  Special local needs labels ID-970007, ID-060008, OR-000033A, OR-000033B, OR-000033C, OR-060009, WA‑920015A, WA-920015B, WA-920015C, and WA-060020. Use 3 to 4 pints/A to control dodder. Apply directly to soil between rows. Spray should not contact carrot plants. Lay-by applications can be in carrots previously treated with herbicides registered for use in carrots. Prowl most effectively controls weeds if adequate rain or irrigation follows within 7 days.
Caution  Do not use on peat or muck soils. Do not plant winter wheat or winter barley in fall after Prowl application at rates above 3 pints/A. Do not feed or graze carrots after application. Do not use screenings from seed processing as feed for livestock.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
probwd Fieldcress, Austrian (Rorippa austriaca) 
•  2,4-D (various products)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
probwd Fluvellin, sharppoint (Kickxia elatine)   
Seedlings of this soft, hairy annual are upright, but as plants mature they develop prostrate stems. Leaves on stems resemble those of bindweed, but fluvellin is in the snapdragon family. It has pale yellow flowers with a narrow spur and a purple upper lip. This weed is spreading into cropland throughout the Willamette Valley of Oregon. Roundleaf fluvellin (Kickxia spuria) is in southern Oregon and seems to be more aggressive than sharppoint fluvellin. They probably react similarly to herbicides.
Little is known about controlling these weeds with herbicides. Sharppoint fluvellin is a problem in spring-seeded grass grown for seed but has not been reported as a problem in established grass fields, which is an indication that it is controlled by the residual herbicides such as diuron, simazine, atrazine, and terbacil that have been used on established grass crops.
In preliminary trials, several herbicides were applied to mature plants of sharppoint fluvellin. These gave good control: Ally, Atrazine, Glean, Ignite, and Lexone. These gave poor control of the mature plants: Amber, Banvel, Basagran, Buctril, Clarity, Classic, Cobra, Garlon, Goal, Gramoxone, Karmex, MCPA, Pursuit, Stinger, 2,4-D. We have received separate reports of good control of small plants of sharppoint with Goal and Harmony Extra at 0.5 oz/A. 
probwd Four-o’clock, wild (Mirabilis nyctaginea)
•  2,4-D (various products)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  imazapic (Plateau)
Rate  0.5% solution as a spot treatment
Remarks  Use a 1% v/v methylated seed oil as an adjuvant. 
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Garlic, wild (Allium vineale) 
•  dicamba (Banvel, Rifle, or Clarity)
Rate  1 to 2 lb ae/A
Time  Early spring, preferably March or early April.
Remarks  Dicamba at the 1-lb rate usually will not seriously injure seed production of grass or grain crops. The 2-lb treatment gives more complete garlic control.
Caution  Dicamba may temporarily sterilize soil west of the Cascades.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  2,4-D LV ester 
Rate  1 to 2 lb ae/A
Time  Early spring, preferably mid-April, before garlic is more than 8 inches tall. Respray annually to achieve effective control.
Remarks  2,4-D LV ester is selective in cereals and grasses. It is very important to respray annually for several years to effectively reduce the garlic stand. This plant produces small dormant bulbs that germinate over several years.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  thifensulfuron + tribenuron (Harmony Extra) 
Rate  0.38 to 0.45 oz ai/A (0.5 to 0.6 oz/A)
Time  When wild garlic is less than 12 inches tall.
Remarks  Control is best on actively growing wild garlic plants when air is 60°F or warmer.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  metsulfuron (Ally and others)
Rate  Ally—0.3 oz ai/A (0.5 oz/A)
Time  Apply to actively growing plants in spring when wild garlic is less than 12 inches tall with 2 to 4 inches of new growth.
Remarks  Using a nonionic or silicone surfactant will increase effectiveness.
Caution  Consult labels for crops where each product can be used.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A)
Time  Apply preemergence or early postemergence in the spring.
Remarks  Use a surfactant for postemergence sprays.
Caution  Do not let spray drift onto sensitive crops. Labeled for use on pasture, range, Conservation Reserve Program (CRP), and noncrop sites only.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Goatgrass, jointed (Aegilops cylindrica) 
•  glyphosate
Rate  0.38 to 0.75 lb ae/A
Time  Apply to actively growing plants emerged before boot stage.
Remarks  Use along field edges and other noncropped areas to prevent spread into bordering fields. Can be used as a spot treatment in certain crops (refer to label).
Caution  Glyphosate is not selective.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  sulfometuron (Oust)
Rate  1 to 1.5 oz ai/A (1.33 to 2 oz/A)
Time  Apply in fall or in late winter before jointed goatgrass is 3 inches tall.
Remarks  Selective to wheatgrass and smooth brome. Other desirable grasses may be stunted, stressed, or injured. Consult the label before using.
Caution  Use on noncropland such as roadsides. Do not let spray to drift onto sensitive crops.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  imazapic (Plateau)
Rate  0.063 to 0.188 lb/A
Time  Apply preemergence for best results.
Remarks  Use lower rates for dry climates and low leaf litter and higher rates as moisture increases and/or leaf litter increases. Selective to most native grasses. Higher rates may suppress seed of some cool-season grasses. 
Caution Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Gorse (Ulex europeaus) 
Control gorse in two stages. First, control established plants. Second, control new plants emerging from seeds that may last more than 30 yr in soil. The most effective control program usually combines herbicides, burning, and cultivation or mowing. Establishing competitive pasture species, forest trees, or other crops helps resist gorse invasion as well as other weeds. A publication on the biology and control of gorse (Gorse, PNW 379, revised July 2001) is available from the Extension Service. When using herbicides, it is crucial to thoroughly wet foliage. Best timing is after bloom drop, but applications at other times usually give good control also.
•  triclopyr ester (Garlon 4 or Remedy) or
•  triclopyr amine (Garlon 3A) or
•  triclopyr + 2,4-D ester (Crossbow) 
Rate  0.5% to 2% concentration for application with a handgun
Time  Apply to actively growing plants after bloom drop in the spring. Garlon 4 and Crossbow can be used for basal bark applications any time of year.
Remarks  Adding 0.25% to 0.5% of a suitable surfactant to Garlon 3A improves results. No surfactant is needed with Garlon 4 or Remedy. Use the higher rates on larger plants and on solid stands of old plants.
Caution  Garlon products are registered for use on rights-of-way, industrial sites, and forestry (release and site preparation). Crossbow and Remedy can be used on permanent pastures and rangeland up to 1.5 lb ae/A. Observe all grazing and harvesting restrictions.
Site of action  Group 4: synthetic auxin
Chemical family  (triclopyr) pryidine; (2,4-D) phenoxy acetic acid
•  picloram (Tordon)
Rate  0.5% concentration for application with a handgun
Time  Apply to actively growing plants after bloom drop in the spring.
Remarks  Adding a suitable surfactant at 0.25 to 0.5% will improve results.
Caution  Most formulations are restricted-use herbicides. Refer to label for grazing restrictions. Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  glyphosate
Rate  1.5 to 3 lb ae/A or 1.5 to 2% solution for handgun application
Time  Apply to actively growing plants after bloom drop in the spring.
Remarks  Adding a recommended surfactant improves results.
Caution  Glyphosate kills grasses and most other desirable species needed to compete with new gorse plants.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  metsulfuron (Escort and others)
Rate  Escort—use 0.6 oz ai/A (1 oz/A)
Time  Apply to actively growing plants after bloom drop in spring.
Remarks  Include a silicon-based surfactant. Application sites differ among products; consult labels.
Caution  Do not let spray drift onto agricultural crops. Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.75 to 1.5 lb ae/A or 0.5% to 1% concentration for handgun application
Time  Apply to actively growing plants after bloom drop in the spring.
Caution  No waiting period between treatment and grazing for nonlactating animals (see label for restrictions on dairy animals). Remove meat animals from treated areas 30 days before slaughter. Rates above 2 lb ai/A may temporarily injure many grass species. Newly seeded grass (see label) may be injured at rates above 0.75 lb ai/A. Do not exceed 8 lb ai/A per season. Kills legumes.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  2,4-D LV ester  (several products)
Rate  0.75 to 1.5 lb ae/A or 0.5 to 1% concentration for handgun application
Time  Apply to actively growing plants after bloom drop in the spring.
Caution  Do not let spray drift onto agricultural crops. Do not graze dairy animals within 7 days after application.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
probwd Gumweed (Grindelia squarrosa) 
•  2,4-D LV ester 
Rate  2 lb ae/A
Time  Apply in early spring when new growth and seedlings are fully emerged.
Remarks  After plants reach the bloom stage, control decreases.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.5 lb ae/A
Time  Apply in early spring from emergence to flower bud stage.
Remarks  May be mixed with 2,4-D to get better control.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon)
Rate  0.25 lb ae/A
Time  Apply in early spring after plants have emerged.
Caution  Most formulations are restricted-use herbicides. See label for grazing restrictions. Avoid drift to potatoes, beans, and many other sensitive broadleaf crops. Do not contaminate water. Do not use picloram in diversified crop areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  metsulfuron (Escort and others)
Rate  Escort—use 0.6 to 1.2 oz ai/A (1 to 2 oz/A) 
Time  Apply to actively growing gumweed in the spring.
Remarks  Using a silicone or nonionic surfactant enhances control. Application sites differ among products at the above rates; consult labels.
Caution  Do not let spray drift onto sensitive crops. Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Halogeton (Halogeton glomeratus) 
•  metsulfuron (Escort and others)
Rate Escort—0.45 oz ai/A (0.75 oz/A)
Time  Apply to actively growing halogeton.
Remarks  Use a surfactant. Application sites differ among products at the above rate; consult labels.
Caution  Do not let spray drift onto sensitive crops. Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  2,4-D LV ester 
Rate  1 to 2 lb ae/A
Time  Apply in early spring when plants are actively growing before bloom stage.
Remarks  Halogeton is poisonous to livestock. Chemical control is effective but will be futile unless desirable plants occupy the site immediately.
Caution  Do not graze after application until plants dry up.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  imazapic (Plateau)
Rate  0.063 to 0.188 lb/A
Time  Apply preemergence or early postemergence.
Remarks  For postemergence timing, use at least 0.094 lb/A plus a surfactant. Selective to most native grasses. Higher rates may suppress seed of some cool-season grasses.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Hawkweed, mouseear (Hieracium pilosella) 
•  2,4-D (various products) or
•  MCPA (various products) or
•  clopyralid (Transline)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (2,4-D and MCPA) phenoxy acetic acid; (clopyralid) pyridine
probwd Hawkweed, orange and yellow (Hieracium aurantiacum and H. pratense)probwd 
•  2,4-D (various products)
Rate  1.43 to 1.9 lb ae/A
Time  Apply to growing hawkweed before buds form.
Remarks  These species may need retreating and/or the higher rate even under ideal conditions.
Caution  Product injures or kills sensitive broadleaf forages. Do not contaminate water.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  dicamba (Banvel, Rifle, or Clarity)
Rate  2 lb ae/A (2 quarts/A)
Time  Apply to growing hawkweed before flowering.
Remarks  Re-treat as needed but do not exceed 2 lb ae/A per season.
Caution  This product will injure or kill sensitive broadleaf forages. Do not contaminate water. See label for timing restrictions for lactating dairy animals. Remove animals for slaughter from treated areas at least 30 days before slaughter.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon 22K)
Rate  0.25 lb ae/A (1 pint/A)
Time  Apply after most basal leaves emerge but before buds form. Fall treatments also may be effective, but research is limited.
Remarks  Consult label for specific site registrations.
Caution  Product will injure or kill sensitive broadleaf forages. Do not contaminate water.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  clopyralid (Transline or Stinger)
Rate  0.25 to 0.375 lb ae/A (0.66 to 1 pint/A)
Time  Apply after most basal leaves emerge but before buds form. Fall treatments also may be effective, although research is limited.
Remarks  Consult labels for specific site registrations.
Caution Product injures or kills sensitive broadleaf forages. Do not contaminate water.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  clopyralid + 2,4-D amine (Curtail) 
Rate  2 quarts/A Curtail
Time  Apply after most basal leaves emerge but before buds form. Fall treatments also may be effective, but research is limited.
Remarks  Consult label for specific site registrations.
Caution Product injures or kills sensitive broadleaf forages. Do not contaminate water.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  triclopyr + clopyralid (Redeem R&P) 
Rate  3 to 4 pints/A
Time  Apply when weeds are actively growing.
Remarks  Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Do not allow drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  aminopyralid (Milestone)
Rate  1 to 1.5 oz ae/A (4 to 6 fl oz/A Milestone)
Time  Apply to actively growing plants in the bolting stage of growth.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Hemlock, poison (Conium maculatum)  
•  2,4-D or
•  MCPA
Rate  1.5 lb ae/A
Time  Apply in seedling to rosette stage of growth.
Remarks  Most effective soon after plants emerge. Adding a wetting agent may enhance control.
Caution  Do not graze treated area until plants have dried up after spraying.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  glyphosate
Rate  0.75 lb ae/A
Time  Apply to actively growing plants before they begin to bolt.
Remarks  Glyphosate is nonselective and will injure or kill grass that might compete with new hemlock seedlings.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  glyphosate (Roundup Pro Concentrate) 
Rate Inject 5 ml of a 5% v/v solution into each leaf cane
Time  Inject with a hand-held device into one leaf cane per plant, 10 to 12 inches above root crown.
Remarks  Mark each plant when injecting it, to avoid retreating.
Caution  Noncrop use only. Total of all treatments must not exceed 8.5 quarts/A of Roundup Pro Concentrate or 1,600 plants/A.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  metsulfuron (Escort and others)
Rate  Escort—0.6 oz ai/A (1 oz/A)
Time  Apply to actively growing plants.
Remarks  Use a nonionic surfactant or silicone surfactant. Application sites differ between products; consult labels.
Caution  Prevent drift to sensitive plants. Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Henbane, black (Hycocyamus niger) 
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ai/A (1 to 2 pints/A Tordon)
Time  Apply in spring when actively growing before full bloom, or in late summer.
Remarks  Tank-mix 1 lb ae/A of 2,4-D with the lower rate of picloram.
Caution  Most formulations are restricted-use herbicides. Do not apply if circumstances favor movement from treatment site.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  metsulfuron (Escort and others)
Rate Escort—0.3 to 0.45 oz ai/A (0.5 to 0.75 oz/A)
Time  Apply to actively growing plants.
Remarks  Using a nonionic or silicone surfactant will increase effectiveness. Application sites differ between products; consult label.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  dicamba (Banvel)
Idaho only
Rate  0.125 to 0.375 lb ai/A (1 to 3 pints/A Banvel)
Time  Apply when plants are in rosette stage of growth. Use higher rates when treating dense or tall vegetative growth.
Remarks  This is a Sandoz Agro, Inc. 2(ee) recommendation for use only within Idaho.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
probwd Hogweed, giant (Heracleum mantegazzianum) 
•  glyphosate
Rate  1.5 lb ae/A
Time  Apply in spring during the bolting stage.
Remarks  Avoid physical contact with the plant.
Caution  Controls grasses as well as other vegetation in treated area.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  glyphosate (Roundup Pro Concentrate) 
Rate Inject 5 ml of a 5% v/v solution into each leaf cane.
Time  Inject with a hand-held device, into one leaf cane per plant 12 inches above root crown.
Remarks  Mark each plant when injecting it, to avoid retreating the same plant. 
Caution  Noncrop use only. Total of all treatments must not exceed 8.5 quarts/A of Roundup Pro Concentrate or 1,600 plants/A.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  imazapic (Plateau)
Rate  0.188 lb ai/A 
Time  Apply in spring during the bolting stage. 
Remarks  Avoid physically contacting plant when applying. Add an appropriate adjuvant to spray mix.
Caution  Consult label on where Plateau can be used. Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Horsebrush, gray or spineless (Tetradymia canescens) 
•  2,4-D LV ester 
Rate  2.5 lb ae/A
Time  Apply in early spring when plants are actively growing.
Remarks  Spot treatment only. Retreatments are necessary to control this resprouting species. Mechanical treatments must control roots 4 to 6 inches deep.
Caution  This plant is poisonous. Do not graze treated areas until plants have dried up after 2,4-D application.
Site of action  Group 4: synthetic auxin.
Chemical family  Phenoxy acetic acid
probwd Horsetail, field (Equisetum arvense) 
•  dichlobenil (Casoron)
Rate  4 lb ai/A granular formulation
Time  Apply in winter or early spring, when moisture is available to leach chemical into soil. In landscape plantings, apply any time and place bark mulch over the treated area to reduce volatilization.
Remarks  Good selective control in many fruits and ornamental plants. Use as a follow-up, supplemental treatment if horsetail resists many soil-applied herbicides. Can apply over labeled ornamental plants or conifer tree nurseries. Apply midwinter immediately before a cold rain to reduce volatility and enhance weed suppression. Weigh and distribute uniformly exact quantities over precisely measured areas. Oregon results over 9 yr suggest that perennial weeds can be suppressed with 4-, 3-, and 2-lb ai/A rates applied in 3 consecutive yr. Grazing livestock is prohibited. (Inhibits cellulose and cell wall formation.)
Caution  See label for precautions on ornamental species and varieties tolerant of dichlobenil.
Site of action  Group 20: inhibits cell wall synthesis Site A
Chemical family  Nitrile
•  MCPA
Rate  1 to 2 lb ae/A
Time  Apply when horsetail fully emerges and before grain or grass is in boot stage.
Remarks  Gives 20 to 30% reduction in field horsetail stands with each spray application. Retreatments are necessary and may be most effective with more than one application per yr. The second application can be to the stubble after harvesting grain fields.
Caution  Apply once or twice a year until horsetail is controlled. Skipping a year means losing the control gained up to that time.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  chlorsulfuron (Telar)
Rate  1 to 1.5 oz ai/A (1.33 to 2 oz/A)
Time  May be applied preemergence or early postemergence.
Remarks  Do not apply to frozen ground. Maintain constant agitation while mixing in spray solution. Add 0.25% v/v nonionic surfactant to the spray mixture. Application rates up to 1 oz ai/A (1.33 oz/A allowed on pasture, rangeland, and Conservation Reserve Program (CRP) sites. Rates above 1 oz ai/A (1.33 oz/A) allowed only on noncropland.
Caution  Avoid contact with sensitive crops. Do not treat powdery, dry soils and light, sandy soils if rain is not likely after treatment.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Horseweed (Marestail) (Conyza canadensis) 
•  aminopyralid (Milestone)
Rate  1 to 1.5 oz ae/A (4 to 6 fl oz/A Milestone)
Time  Apply to actively growing plants.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed.  Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  glyphosate
Rate  0.75 to 1.5 lb ae/A 
Time  Apply while horseweed is actively growing and less than 12 inches tall.
Remarks  Glyphosate-resistant horseweed is reported throughout the United States. 
Caution  Controls grasses as well as other vegetation in treated area.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  2,4-D LV ester 
Rate  1 lb ae/A 
Time  Apply when horseweed is in the seedling to rosette stage of growth.
Remarks  Plants should be actively growing at time of treatment.
Caution  Avoid drift to sensitive crops and desirable vegetation. This product will injure or kill sensitive broadleaf plants.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.25 lb ae/A
Time  Apply in the seedling to rosette stage.
Remarks  Plants should be actively growing at time of application.
Caution  Avoid drift to sensitive crops and desirable vegetation. This product will injure or kill sensitive broadleaf plants.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  diflufenzopyr + dicamba (Distinct) 
Rate  4 oz/A
Time  Apply in the seedling to rosette stage.
Remarks  Plants should be actively growing at time of application.
Caution  Avoid drift to sensitive crops and desirable vegetation. This product will injure or kill sensitive broadleaf plants.
Site of action  (diflufenzopyr) Group 19: inhibits indole acetic acid transport; (dicamba) Group 4: synthetic auxin
Chemical family  (diflufenzopyr) semicarbazone; (dicamba) benzoic acid
•  flumioxazin (Chateau or Payload)
Rate  2 to 6 oz ai/A (4 to 12 oz/A). Rate depends on application timing and soil type and organic matter.
Time  May be applied preemergence or postemergence to small, actively growing horseweed.
Remarks  Preemergence treatments require rain to move into the soil. Can be used in several crops.
Caution  Note recropping restriction intervals on the label.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  N-phenylphthalimide
•  clopyralid (Stinger or Transline)
Rate  0.125 to 0.188 lb ae/A
Time  Apply to actively growing plants up to the five-leaf stage.
Remarks  See label for registered sites.
Caution  Consult label for crop rotation restrictions before using these products. Several crops may be injured up to 4 yr after application.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Houndstongue (Cynoglossum officinale) 
•  2,4-D LV ester 
Rate  2 lb ae/A
Time  Early spring to actively growing plants before they bloom.
Remarks  Sticky seeds can contaminate wool. Mowing before seed production helps alleviate wool contamination.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  metsulfuron (Escort and others)
Rate  Escort: 0.6 oz ai/A (1 oz/A)
Time  Any time plants are growing well. 
Remarks  Application sites differ between products; see labels.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  picloram (Tordon)
Rate  0.5 lb ae/A
Time  Any time plants are growing well.
Remarks  Reported to give fair to good control.
Caution  Most formulations are restricted-use herbicides.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb/A
Time  Apply to actively growing plants.
Remarks  Use lower rates if rosettes are small; increase rate if rosettes are large or bolting. Selective to most native grasses. Higher rates may suppress seed of some cool-season grasses.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Iris, wild (Iris spp.) 
•  2,4-D LV ester 
Rate  5 lb ae 2,4-D in 100 gal water
Time  Apply in the early bloom stage.
Remarks  Foliage must be thoroughly wet.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  metsulfuron (Escort and others)
Rate  Escort—0.6 ai/A (1 oz/A)
Time  Apply to actively growing plants.
Remarks  Use a surfactant to increase effectiveness. Application sites differ among products; consult labels.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  imazapic (Plateau)
Rate  0.188 lb ae/A
Time  Apply postemergence at the late boot or bloom stage.
Remarks  Use a methylated seed oil at 1 quart/A; do not exceed 25 gal/A spray volume.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  imazapyr (Habitat)
Rate  0.75% v/v product
Time  Apply prebloom or in the fall.
Remarks  Use a surfactant the label recommends.
Caution  Before use, note rotation and other restrictions on label
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  glyphosate
product labeled for aquatic sites
Rate  5% solution of a 4 lb ae (5.4 lb ai) glyphosate
Time  Apply prebloom or in the fall.
Remarks  Use a nonionic surfactant recommended for aquatic sites
Caution  Glyphosate is nonselective and may injure or kill desirable species.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
probwd Ivy, common or English (Hedera helix) 
•  triclopyr amine  (Garlon 3A, Brush-B-Gone, or Brush Killer) or
•  triclopyr ester  (Garlon 4, Pathfinder, or Vinex) or
•  glyphosate  (Accord, Glypro, or Rodeo)
Rate  at least 41% active ingredient (3 lb ae or 4 lb ai) glyphosate
Remarks  Basal bark application―apply 33% dilution of triclopyr or glyphsate to exposed stems after stripping the leaves from stems near ground level. 
Cut stem application (most effective method)―cut each vine stem close to the ground and treat freshly cut surfaces (preferably within 5 min) with a 33% solution of triclopyr amine or glyphosate mixed in water. Do not dilute products such as Brush-B-Gone and Brush Killer. Roundup Pro Concentrate (50.2% formulation) may be diluted with water.  
Foliar application―from summer to fall, apply to leaves a 2 to 5% solution of triclopyr ester mixed in water with a nonionic surfactant. Fully coat foilage. Some control may be possible with glyphosate as a 2 to 4% dilution using at least a 41% (3 lb ae or 4 lb ai glyphosate), but repeat applications will probably be necessary. Broadcast applications of triclopyr will cause less damage to desirable grasses.
Manual and mechanical―Pull vines on the ground by hand and discard. Cut vines will root easliy. Cut climbing vines near the gournd, then pry the vines from the tree or structure. Once the vines are cut they will eventually die and fall from the tree, usually after the first extended hot and dry period. Ocassionally vines will be embedded in the trunk of the tree. This makes control by both hand and chemicals very difficult; continual removal of sprouts will be needed.
Site of action  (triclopyr) Group 4: synthetic auxin; (glyphosate) Group 9: inhibits EPSP.
Chemical family  (triclopyr) pyridine; (glyphosate) none generally accepted
probwd Jimsonweed (Datura stramonium) 
•  alachlor (Lasso) or
•  atrazine (AAtrex) or
•  bromoxynil (Buctril) or
•  clomazone (Command) or
•  clopyralid (Stinger or Transline) or
•  diuron (Karmex) or
•  glyphosate or 
•  metolachlor (Dual) or
•  metribuzin (Sencor)
•  oxyfluorfen (Goal) or
•  paraquat (Gramoxone Max) or
•  picloram (Tordon) or
•  terbacil (Sinbar) or
•  2,4-DB (Butyrac)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  (alachlor and metolachlor) Group 15: unknown; (atrazine, metribuzin, and terbacil) Group 5: photosystem II inhibitor; (bromoxynil) Group 6: photosystem II inhibitor; (clomazone) Group 13: inhibits DOXP synthase; (clopyralid, picloram, and 2,4-DB) Group 4: synthetic auxin; (diuron) Group 7: photosystem II inhibitor; (glyphosate) Group 9: inhibits EPSP synthase; (oxyfluorfen) Group 14: protoporphyrinogen oxidase inhibitor; (paraquat) Group 22: photosystem I electron diverter 
Chemical family  (alachlor and metolachlor) chloroacetamide; (atrazine) triazine; (bromoxynil) nitrile; (clomazone) isoxazolidone; (clopyralid and picloram) pyridine; (diuron) urea; (glyphosate) none generally accepted; (metribuzin) triazinone; (oxyfluorfen) diphenylether; (paraquat) bipyridilium; (terbacil) uracil; (2,4-DB) phenoxy acetic acid
probwd Johnsongrass (Sorghum halepense) 
•  glyphosate
Rate  2.25 lb ae/A
Time  Apply at heading time to actively growing plants.
Remarks  Rain within 6 hr after application may reduce effectiveness. Spray to cover but not to point of runoff.
Caution  Glyphosate controls other grasses and vegetation in treated areas.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  MSMA (Bueno or Trans-Vert)
Rate  2.25 lb ai/A
Time  This herbicide is foliar-active; apply to rapidly growing foliage.
Remarks  Use with caution on or near ornamentals (see label). Can mix with 2,4-D for broader control on noncropland. MSMA is inactivated by soil surface adsorption.
Caution  Keep liquid or dust away from eyes. Wash eyes immediately with water if exposed.
Site of action  Group 17: not well understood
Chemical family  Organoarsenical
•  sethoxydim (Poast)
Rate  0.28 to 0.47 lb ai/A (1.5 to 2.5 pints/A)
Time  Apply to actively growing johnsongrass when the plant is 15 to 25 inches tall.
Remarks  Apply with 2 pints/A crop oil concentrate. Sethoxydim acts very slowly, taking at least 2 wk and often 4 wk to show herbicide effectiveness. Do not apply to stressed grasses. If johnsongrass regrows, repeat application when it is 6 to 8 inches tall.
Caution  Do not apply if rain is expected within 1 hr.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  fluazifop (Fusilade DX)
Rate  0.25 to 0.375 lb ai/A (2 to 3 pints/A)
Time  Apply to actively growing johnsongrass 8 to 18 inches tall but before boot stage.
Remarks  Apply with 1% v/v crop oil concentrate or 0.25% v/v nonionic surfactant. Fluazifop acts very slowly, taking at least 2 wk and often 4 wk to show effectiveness. Do not apply to stressed grasses. If weed regrows, repeat application at 0.187 to 0.375 lb ai/A.
Caution  Do not use crop oil concentrate if treating johnsongrass in ornamentals. Do not apply if rain is expected within 1 hr.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  fenoxaprop (Acclaim or Horizon)
Rate  0.15 to 0.25 lb ai/A
Time  Apply to actively growing seedlings with two to five leaves. Larger plants are more difficult to control. Apply to rhizome johnsongrass that is 24 to 60 inches tall and growing actively.
Remarks  Rhizome johnsongrass is only suppressed. Do not apply within 3 wk after mowing.
Caution  Do not use a crop oil or surfactant.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  imazapic (Plateau)
Rate  0.188 lb ae/A
Time  Apply postemergence, at the late-boot or bloom stage.
Remarks  Use a methylated seed oil at 1 quart/A; do not exceed 25 gal/A spray volume.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  imazapic + glyphosate (Journey) 
Rate  21 to 32 oz/A
Time  Apply postemergence to grass when it is 18 to 24 inches at the whorl.
Remarks  Add a suitable surfactant to the spray mix. See label for details.
Caution  Before using, note crop rotation restrictions. 
Site of action  (imazapic) Group 2: acetolactate synthase (ALS) inhibitor; (glyphosate) Group 9: inhibits EPSP synthase
Chemical family  (imazapic) imidazolinone; (glyphosate) none generally accepted
probwd Knapweeds (Centaurea spp. and Acroptilon repens) 
The following herbicides usually control treated plants. Plants often regrow, so plan annual applications for several years. Control of regrowth and of new seedlings is much better if a competitive crop or sod is established. A perennial grass is the logical choice because, except for glyphosate, the herbicides listed here will not kill established grasses.
•  glyphosate
Rate  3 lb ae/A
Time  Apply to actively growing knapweed when most plants are at bud stage.
Remarks  Glyphosate kills many knapweed plants but also kills grass that might compete with new knapweed seedlings. Russian knapweed is not controlled. When using glyphosate, follow by seeding with a locally adapted grass.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ae/A (1 lb ae/A for Russian knapweed)
Time  Apply in late spring before or during flower stem elongation.
Remarks  A selective treatment that, at the suggested rate, will not damage perennial grasses. Treatment made in bud stage may not prevent seed production in the year of application. However, seed germination is markedly reduced.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water or use in diversified crop areas. Potatoes, beans, and most other broadleaf crops are sensitive to picloram.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  2,4-D
Rate  1 to 2 lb ae/A (4 to 8 lb ae/A for Russian knapweed)
Time  Apply at the early stage of flower stem elongation (late April to early May).
Remarks  Treatment will control only plants emerged at time of spraying.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  clopyralid + 2,4-D amine (Curtail) 
Rate  2 to 4 quarts/A Curtail
Time  Apply after most rosettes emerge but before flower stem elongates.
Remarks  Lower rate for in-crop cereal grain application; higher rates for fallow, postharvest, and Conservation Reserve Program (CRP) applications. Consult label for specific directions. CRP applications for established grass only. Apply in enough total spray volume to ensure good coverage for diffuse and spotted knapweed.
Caution  Consult label for crop rotation restrictions before using product. Several crops may be injured up to 4 yr after application.
Site of action  Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  clopyralid (Stinger or Transline)
Rate  0.25 to 0.5 lb ae/A (0.66 to 1.33 pints/A). Labeled rates vary with crops.
Time  Up to the bud stage of knapweeds.
Remarks  Results are best if applied to actively growing weeds. See labels for registered sites.
Caution  Consult label for crop rotation restrictions before using Stinger. Several crops may be injured up to 4 yr after application.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  triclopyr + clopyralid (Redeem R&P) 
Rate  1.5 to 2 pints/A (2.5 to 4 pints/A for Russian knapweed)
Time  Apply from rosette to early bolt stage when weeds are actively growing. Russian knapweed should be in early bud to early flower.
Remarks  Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Do not allow drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  aminopyralid (Milestone)
Rate  1 to 1.75 oz ae/A (4 to 7 fl oz/A Milestone). Rate of application will depend on knapweed species to be controlled.
Time  Consult label for optimum timing. Diffuse and spotted knapweed—apply to actively growing plants in fall or in spring from rosette to bolting growth stages. Russian knapweed—apply in spring and summer to plants from bud to flowering stage; in fall, to dormant plants.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed.  Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  imazapic (Plateau)
Rate  0.188 lb ai/A for Russian knapweed 
Time  Apply in fall or early winter after Russian knapweed has grown old.
Remarks  Use 1 quart/A methylated seed oil as the adjuvant. Selective to most native grasses. Higher rates may suppress seed of some cool-season grasses. 
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  diflufenzopyr + dicamba (Overdrive) 
Rate  0.26 to 0.35 lb ae/A (6 to 8 oz/A)
Time  Apply to rosettes.
Remarks  Add a surfactant to the spray mix.
Caution  Avoid drift to sensitive crops. Will kill legumes.
Site of action  (diflufenzopyr) Group 19: inhibits indole acetic acid transport; (dicamba) Group 4: synthetic auxin
Chemical family  (diflufenzopyr) semicarbazone; (dicamba) benzoic acid
probwd Knotweed, Japanese, or fleeceflower  (Polygonum cuspidatum) 
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.25 lb ae dicamba mixed with 1 gal water/400 sq ft
Time  Apply in late August to new regrowth since plant was cut back in June.
Remarks  Apply as a basal spray to the stems at ground level.
Caution  Do not apply in areas where roots of desirable plant species are growing.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  glyphosate
Rate  Spot treatment—0.06 lb ae (2.67 fl oz) glyphosate with 1 gal water
Time  Apply as a coarse spray when weeds are actively growing and most are at bud to early flowering growth stage.
Remarks  Spray for complete, uniform coverage but not to the point of runoff.
Caution  Glyphosate is nonselective: it injures or kills any vegetation it contacts.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  glyphosate (Roundup Pro Concentrate) 
Rate  Inject 5 ml/stem
Time  Inject with a hand-held device into hollow stem of actively growing plants between second and third internodes.
Remarks  Mark each stem when making the injection to avoid reapplying. 
Caution  Noncrop use only. Total of all treatments must not exceed 8.5 quarts/A of Roundup Pro Concentrate or 1,600 stems/A.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  imazapyr (Arsenal or Habitat)
Rate  0.5 to 1 lb/A or 1% solution + 0.25% surfactant.
Time  Apply in midsummer, after seedhead forms, up to killing frost.
Remarks  Spray to cover plants but not to runoff. Habitat is labeled for aquatic sites.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Larkspur, tall or duncecap (Delphinium occidentale)  
•  picloram (Tordon)
Rate  1  lb ae/A
Time  Apply to actively growing plants from flower stalk formation to early seed development.
Remarks  Poisonous plant.
Caution  Most formulations are restricted-use herbicides. Do not graze until plants have dried up after spray application. Refer to label for grazing restrictions. Do not contaminate water. Potatoes, beans, and many other crops are very sensitive to picloram. Do not use in diversified cropping areas. For rates exceeding 0.5 lb ae/A (1 quart/A), apply only as a spot treatment not to exceed 25% of an owner’s acreage in a particular watershed in a single season.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  metsulfuron (Escort)
Rate  0.9 to 1.2 oz ai/A (1.5 to 2 oz/A)
Time  After weeds emerge.
Remarks  Use a surfactant to increase effectiveness.
Caution  Apply only to noncropland.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Lepyrodiclis (Lepyrodiclis holosteoides) 
Remarks  Control is unknown. 
probwd Lupine species (Lupinus spp.) 
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ae/A
Time  Apply to actively growing lupine at the early bud stage.
Remarks  Several species of lupine are poisonous to livestock.
Caution  Most formulations are restricted-use herbicides. Do not graze until plants dry up after spray applications. See label for grazing restrictions. Do not contaminate water. Potatoes, beans, and many other crops are very sensitive to picloram. Do not use in diversified cropping areas. For rates above 0.5 lb ae/A (1 quart/A), apply only as a spot treatment not to exceed 25% of a landowner’s acreage in a given watershed in a single season. Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  2,4-D LV ester 
Rate  2 lb ae/A
Time  Apply at the early bud stage to actively growing plants.
Remarks  Several species of lupine are poisonous to livestock.
Caution  Do not graze until plants dry up after application. Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  metsulfuron (Escort)
Rate  0.9 oz ai/A (1.5 oz/A)
Time  Apply to actively growing plants.
Remarks  Use a surfactant to increase effectiveness. Spray to wet.
Caution  Apply only to noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Lythrum, purple, or purple loosestrife  (Lythrum salicaria) 
•  glyphosate (Rodeo)
Rate  1% solution with hand-held equipment
Time  Apply to actively growing plants at full to late flowering stage. Seedlings may be effectively treated early in the season after a fall application to mature plants.
Remarks  Use 0.5% v/v nonionic surfactant. Thoroughly wet foliage but avoid runoff.
Caution  Glyphosate is nonselective. It will injure or kill vegetation it contacts.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  triclopyr (Garlon 4 or Garlon 3A)
Rate  1.5 to 2% concentration for application with handgun
Time  When plant is in midbloom to full-bloom stage or early in season on seedlings.
Remarks  Labeled for use on nonirrigation ditch banks and in seasonally dry wetlands.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  imazapyr (Habitat)
Rate  0.25 to 0.5 lb ae/A
Time  Apply to actively growing loosestrife after midbloom until killing frost. 
Remarks  Add suitable adjuvant to spray solution.
Caution  Before using, note crop rotation restrictions. Do not apply to root zone of desirable trees.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  metsulfuron (Escort and others)
Rate  Escort—0.6 oz ai/A (1 oz/A)
Time  Apply to actively growing plants.
Remarks  Using a nonionic or silicone surfactant increases effectiveness. Before using, check label to see whether product can be used on the type of site intended. Application sites differ among products; consult labels.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Mallow, Venice (Hibiscus trionum) 
•  alachlor (Lasso) or
•  bentazon (Basagran) or
•  bromoxynil (Buctril) or
•  chlorsulfuron (Glean) or
•  dicamba (various products) or
•  glyphosate (Roundup) or
•  metribuzin (Sencor) or
•  oxyfluorfen (Goal) or
•  paraquat (Gramoxone Max) or
•  picloram (Tordon) or
•  2,4-D (various products)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  (alachlor) Group 15: unknown; (bentazon and bromoxynil) Group 6: photosystem II inhibitor; (chlorsulfuron) Group 2: acetolactate synthase (ALS) inhibitor; (dicamba and 2,4-D) Group 4: synthetic auxin; (glyphosate) Group 9: inhibits EPSP synthase; (metribuzin) Group 5: photosystem II inhibitor; (oxyfluorfen) Group 14: protoporphyrinogen oxidase inhibitor; (paraquat) Group 22: photosystem I electron diverter
Chemical family  (alachlor) chloroacetamide; (bentazon) benzothiadiazole; (bromoxynil) nitrile; (chlorsulfuron) sulfonylurea; (dicamba) benzoic acid; (2,4-D) phenoxy acetic acid; (glyphosate) none generally accepted; (metribuzin) triazine; (oxyfluorfen) diphenylether; (paraquat) bipyridilium
probwd Milkweed (Asclepias speciosa) 
•  picloram (Tordon)
Rate  1 lb ae/A
Time  Apply at bud to early bloom to actively growing milkweed.
Caution  Most formulations are restricted-use herbicides. See label for grazing restrictions. Do not contaminate water. Potatoes, beans, and many other crops are very sensitive to picloram. Do not use in diversified cropping areas. Apply rates over 0.5 lb ae/A (1 quart/A) only as a spot treatment not to exceed 25% of a landowner’s acreage in any given watershed in a single season.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  glyphosate
Rate  2.25 lb ae/A
Time  Apply to actively growing milkweed that has reached the late bud to flower stage of growth.
Remarks  After small grain harvest or mowing, let milkweed regrow to mature stage before treating. Allow 7 days or more after application before tillage.
Caution  Glyphosate controls grasses as well as other vegetation in treated areas.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
probwd Nightshade, silverleaf (Solanum elaeagnifolium) 
•  glyphosate or
•  picloram (Tordon)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  (glyphosate) Group 9: inhibits EPSP synthase; (picloram) Group 4: synthetic auxin
Chemical family  (glyphosate) none generally accepted; (picloram) pyridine
•  imazapyr (Arsenal)
Rate  1 lb ae/A
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Nutsedge, yellow (Cyperus esculentus)
•  glyphosate
Rate  2.25 lb ae/A as a broadcast spray, or a 1% solution using hand-held equipment
Time  When nutsedge is actively growing in midseason but before new tubers begin to form, usually by June 15 to July 1.
Remarks  Nutsedge can be reduced by encouraging active growth and applying glyphosate once or more often when several nutsedge leaves are present but before new tubers begin to form.
Caution  Retreatment is important. Glyphosate controls grasses as well as other vegetation in the treated area.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  EPTC (Eptam)
Rate  3 to 6 lb ai/A
Time  Apply before final seedbed preparation in the spring.
Remarks  Incorporate immediately by disking two directions or rototill to distribute 2 to 3 inches deep. Apply only to soil dry on the surface and disk immediately. Use before planting beans and potatoes. Treatment suppresses nutsedge for one season only.
Caution  Incorporate 2 to 3 inches into soil immediately after application.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  EPTC with safener (Eradicane or Genate) or
•  butylate with safener (Sutan)
Rate  4 to 6.14 lb ai/A, depending on soil type and infestation; see label.
Time  Apply preplant and incorporate immediately and thoroughly.
Remarks  These herbicides are selective in corn. Perennial weeds must be turned under and chopped up thoroughly before treatment. See label for additional application and incorporation instructions. Suppresses emergence of new shoots from yellow nutsedge tubers but does not necessarily kill them.
Caution  Do not use EPTC without safener on ‘Golden Jubilee’ sweet corn west of the Cascades. Do not exceed 4 lb ai/A EPTC with safener on sweet corn.
Site of action  (both) Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  (both) hiocarbamate
•  dichlobenil (Casoron)
Rate  150 lb/A of 4% granules
Time  Apply in winter just before a period of rain, or in spring just before applying bark mulch in landscape plantings.
Remarks  Incorporate by rototilling or rain. Selective in some fruits and ornamentals (see label). Apply midwinter immediately before a cold rain to reduce volatility and enhance weed suppression. Weigh and distribute uniformly exact quantities over precisely measured areas. Oregon results from over 9 yr suggest perennial weeds can be suppressed with 4-, 3-, and 2-lb ai/A rates applied in 3 consecutive years. Grazing livestock is prohibited. In noncrop-land areas only, up to 250 to 500 lb of 4% granules can be used for nutsedge control. Inhibits cellulose and cell wall formation.
Caution  Do not breathe dust or allow contact with eyes or skin.
Site of action  Group 20: inhibits cell wall synthesis Site A
Chemical family  Nitrile
•  bentazon (Basagran)
Rate  0.75 to 1 lb ai/A
Time  Use split applications: first when nutsedge is 6 to 8 inches tall, again 7 to 10 days later.
Remarks  Corn may show injury (light specks on leaves) but generally outgrows it in 20 days. Bentazon is also registered for several other crops. Use at least 20 gal/A water and at least 40 psi by ground. For aerial application, use at least 5 gal/A water and at least 40 psi.
Caution  Avoid applying during drought or unseasonably cold weather. Unsatisfactory results can be expected if daytime temperatures do not reach at least 70°F during the week after applying.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Benzothiadiazole
•  alachlor (Lasso or Micro-Tech)
Rate  1.5 to 4 lb ai/A
Time  Use a preplant incorporation application.
Remarks  Selective in corn and dry beans. Controls most annual grasses and certain annual broadleaf weeds. Absorbed mainly by germinating plant shoots; seems to inhibit protein synthesis.
Caution  A restricted-use herbicide. Avoid contact with the eyes and skin.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  S-metolachlor  (Dual II Magnum or Dual Magnum)
Rate  Refer to label
Time  Use preplant incorporated.
Remarks  Incorporate uniformly to 2 inches before planting. Use lower rates on coarse soils.
Caution  May cause skin sensitization reactions in some people. Do not breathe spray mist.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  halosulfuron (Permit, Sandea, or SedgeHammer)
Rate  0.5 to 1 oz ai/A (0.67 to 1.33 oz/A)
Time  Labels differ. For example, apply SedgeHammer to yellow nutsedge in the three- to five-leaf stage. Apply SedgeHammer in turf to yellow nutsedge in the three- to eight-leaf stage of growth.
Remarks  Halosulfuron is labeled on several crops. Consult labels for stage of crop or turf growth. Add 1 to 2 quarts nonionic surfactant or crop oil concentrate per 100 gal spray solution for broadcast applications. A second halosulfuron application may be required 6 to 10 wk after the first.
Caution  Do not exceed 1.5 oz ai/A (2 oz/A) of Permit or Sandea or two applications per season. Do not exceed exceed 0.4 oz ai/A (5.33 oz/A) of SedgeHammer or four applications per season. Note labels for information on recropping, reseeding, and site of application.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb ai/A
Time  Apply postemergence when plants have bolted.
Remarks  Add 1 quart/A methylated seed oil; do not exceed 25 gal/A spray volume.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Oatgrass, tuber (Arrhenatherum elatius var. bulbosum) 
•  glyphosate
Rate  1 to 2 lb ae/A
Time  When plants are at least 15 inches tall and growing rapidly.
Remarks  Established stands are controlled best by the 2-lb rate applied after May 1 to undisturbed sites. Newly sprouted corms are controlled with the 1-lb rate, but less herbicide will move into attached unsprouted corms. A single application to dormant corms gives only limited long-term control; tillage and repeated applications will be required.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
probwd Olive, Russian (Elaeagnus angustifolia) 
•  2,4-D LV ester 
Rate  2 lb ae/A
Time  When leaves are fully developed.
Remarks  Two to three annual retreatments may be necessary for complete control.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  2,4-D + triclopyr (Crossbow) 
Rate  1.5% spray solution
Time  Apply during active growth, after full leaf expansion, and when moisture and temperature are favorable.
Remarks  This product also can be used in dormant stem and conventional basal applications. Refer to label for additional instructions. Retreatment may be necessary.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (2,4-D) pyridine; (triclopyr) phenoxy acetic acid
•  glyphosate
Rate  2 cc (ml) per inch of trunk diameter or 5% solution applied to foliage
Time  Apply undiluted to frill cuts or apply to foliage after the Russian olive fully leafs out.
Remarks  Spray to wet foliage but not to the point of runoff.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  imazapyr (Arsenal)
Rate  2 cc (ml) per inch of trunk diameter or 0.75% solution of the 2 lb ai/gal applied to foliage
Time  Apply undiluted to frill cuts or apply to foliage after the Russian olive fully leafs out. 
Remarks  Spray to wet foliage but do not allow spray to run off foliage.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Parsley, hedge (Torilis arvensis) 
•  simazine (Princep)
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label directions.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazine
probwd Pepperweed, perennial (Lepidium latifolium) 
•  2,4-D amine
Rate  4 lb ae/A
Time  Apply at the bud stage of growth.
Remarks  Repeat treatments if needed. Good grass cover helps control perennial pepperweed.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  metsulfuron (Escort)
Rate  Escort: 0.6 to 1.2 oz ai/A (1 to 2 oz/A)
Time  Apply to actively growing perennial pepperweed.
Remarks  Selective to grasses. Use a surfactant.
Caution  Do not allow spray to drift onto sensitive crops. Apply only to noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A)
Time  Apply in fall or in spring up through bloom stage.
Remarks  Adding surfactant and/or 2,4-D improves control.
Caution  Do not let spray drift onto sensitive crops. Labeled for use on pasture, range, Conservation Reserve Program (CRP), and noncropland only.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb ai/A
Time  Apply after blossoms open (full bloom) until plants desiccate. Fall rosettes also may be treated if moisture permits.
Remarks  Lightly cover foliage with spray solution. Add 1 quart/A methylated seed oil.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Poison-oak and poison-ivy (Toxicodendron spp.) 
•  glyphosate (E-Z-Ject)
Rate  Follow label instructions on number of capsules per stem.
Time  Apply when plants are actively growing at or beyond early bloom stage.
Remarks  The E-Z-Ject system of application will not harm desirable species.
Caution  Capsules must penetrate woody bark for control.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  glyphosate
Rate  3 to 3.75 lb ae/A broadcast or apply as a 2% solution with hand-held equipment.
Time  Apply when plants are actively growing at or beyond early to full bloom stage. Results are best if applied after fruit forms. Make late summer or fall treatments before leaves lose their green color. Use higher rates for plants that have reached woody stage of growth.
Remarks  Treat foliage when plants are growing rapidly. In orchards, prevent spray mist from contacting foliage, green bark, suckers, or fruit of crop trees or other desirable vegetation. If spray contacts immature bark on main trunk, serious localized or translocated damage can result. Roundup is a nonresidual herbicide requiring subsequent seedling control.
Caution  Controls grasses and other vegetation in treated area.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  triclopyr ester (Garlon 4) or
•  triclopyr amine (Garlon 3A) or
•  triclopyr + 2,4-D ester (Crossbow) 
Rate  Spot treat—use 3 lb ae Garlon 4 or 2.25 lb ae Garlon 3A with 100 gal water; or 1 pint Crossbow in 12 gal water. Broadcast—use 4 to 8 lb ae/A Garlon 4, or 6 to 9 lb ae/A Garlon 3A, or 1 to 2 quarts/A of Crossbow.
Time  Apply when plants are actively growing.
Remarks  Foliage must be thoroughly wet.
Caution  Garlon products are registered for use on rights-of-way, industrial sites, and forestry (release and site preparation). Crossbow can be used on permanent pastures and rangeland up to 1.5 lb ae/A. Observe all grazing and harvesting restrictions.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (triclopyr) pyridine; (2,4-D) phenoxy acetic acid
probwd Pricklypear (Opuntia polyacantha) 
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ae/A
Time  Apply in May to July. Timing is not critical.
Caution  Most formulations are restricted-use herbicides. See label for grazing restrictions. Do not contaminate water. Potatoes, beans, and many other crops are very sensitive to picloram. Do not use in diversified cropping areas. Apply rates over 0.5 lb ae/A (1 quart/A) only as a spot treatment not to exceed 25% of a landowner’s acreage in any given watershed in a single season.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Proso millet, wild (Panicum miliaceum) 
•  fluazifop (Fusilade DX)
Rate  0.09 lb ai/A (0.375 pints/A)
Time  Apply to actively growing weeds 2 to 8 inches tall but before tillering or heading.
Remarks  See label for crops, ad sites, and specific rates. Apply with 1% (v/v) crop oil concentrate or 0.25% (v/v) nonionic surfactant. Acts very slowly, taking at least 2 wk and often 4 wk to show effectiveness. Do not apply to stressed grasses.
Caution  Do not use crop oil concentrate if treating in ornamentals. Do not apply if rain is expected within 1 hr.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  sethoxydim (Poast)
Rate  0.19 lb ai/A (1pint/A)
Time  Apply to actively growing wild proso millet.
Remarks  See label for crops, size of grass, and sites sethoxydim may be used on and for specific rates. Apply with 2 pints/A crop oil concentrate. Acts very slowly, taking at least 2 wk and often 4 wk to show herbicide effectiveness. Do not apply to stressed grasses.
Caution  Do not apply if rain is expected within 1 hour.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  fenoxaprop (Acclaim or Horizon)
Rate  0.15 to 0.25 lb ai/A
Time  Apply to actively growing plants with at least two leaves. Larger plants are harder to control.
Remarks  Refer to product label for crops and sites on which fenoxaprop may be used.
Caution  Do not use a crop oil or surfactant.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  nicosulfuron (Accent)
Rate  0.5 to 1 oz ai/A (0.66 to 1.33 oz/A Accent)
Time  Apply when wild proso millet is 1 to 4 inches tall.
Remarks  Accent is registered for use in field corn and popcorn. Consult seed company representative before applying to field corn grown for seed or to any popcorn varieties. Special local needs label WA-960023 for certain varieties of sweet corn grown for processing; see label.
Caution  Take special precautions when using for wild proso millet control in sweet corn. Read label about applications where organophosphate insecticides have been used. Consult labels for rotation crop guidelines.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  topramezone (Impact)
Rate  0.0165 lb ai/A (0.75 oz/A)
Time  Apply postemergence to actively growing wild proso millet that is 3 to 8 inches tall.
Remarks  Controls wild proso millet and many annual broadleaf weeds but does not provide residual control. Add methylated seed oil or crop oil concentrate at 1 to 1.5% v/v and UAN fertilizer or ammonium phosphate at 1.2 to 1.5% v/v to the spray solution. Spray-grade ammonium sulfate at 8.5 to 17 lb/100 gal of water may be substituted for the nitrogen fertilizers. 
Caution  Apply only once per growing season. Read label carefully to determine crops that can be planted the next year.
Site of action  Group 28: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family  Triketone
probwd Puncturevine (Tribulus terrestris) 
•  2,4-D amine or
•  2,4-D LV ester
Rate   1 to 2 lb ae in 10 to 20 gal water for spot treatments.
Time  Apply every 3 wk during growing season or when new seedlings appear.
Remarks Seed will germinate throughout the summer when moisture is available.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  MSMA (Bueno or Trans-Vert)
Rate  2 to 4 lb ai/A
Time  Apply after puncturevine emerges. Best results in seedling stage of growth.
Remarks  MSMA is more active above 70°F. Regrowth after rain or overhead irrigation may need respraying.
Caution  Keep liquid or dust away from eyes. Wash eyes immediately with water if exposed.
Site of action  Group 17: not well understood
Chemical family  Organoarsenical
•  paraquat (Gramoxone Max)
Rate  0.38 to 0.49 lb ai/A
Time  Apply as a postemergence spray to puncturevine foliage.
Remarks  Results are best when puncturevine is in the seedling stage. Add 8 to 16 fl oz/100 gal nonionic surfactant to spray mix. Paraquat is a contact herbicide requiring thorough spray coverage. Puncturevine emerging after application will not be controlled.
Caution  A restricted-use herbicide. Do not use around homes or other areas contacted by children or pets. Do not breathe spray mist.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
•  chlorsulfuron (Telar)
Rate  1 oz ai/A (1.5 oz/A)
Time  Apply late fall or late winter preemergence to growth. Needs moisture to activate.
Remarks  May be used selectively or tank-mixed with other selective or bareground herbicides. Use only on pasture, range, Conservation Reserve Program (CRP), and noncropland.
Caution  Do not let spray drift onto sensitive crops.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  bromacil + diuron (Krovar I DF)
Rate  8 lb ai/A (10 lb/A)
Time  Apply before weeds emerge.
Remarks  Rain is needed to activate this herbicide.
Caution  Nonselective weed control. Do not apply where desirable plant roots extend.
Site of action  Group 5: photosystem II inhibitor
Chemical family  (bromacil) uracil; (diuron) urea
•  norflurazon (Solicam)
Rate  Refer to label. Adjust rates depending on soil texture and organic matter.
Time  Apply in fall to spring, before puncturevine emerges.
Remarks  Remove existing weeds mechanically or by a suitable postemergent herbicide.
Site of action  Group 12: bleaching; inhibits carotenoid biosynthesis
Chemical family  Pyridazinone
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb ai/A
Time  Apply early postemergence when plants are cracking.
Remarks  Add 1 quart/A methylated seed oil; do not exceed 25 gal/A spray volume.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  bentazon (Basagran)  +
•  imazamox (Raptor)
Rate  0.75 to 1 lb ai/A bentazon + 0.031 lb ai/A imazamox (4 oz/A Raptor)
Time  Apply to small, actively growing puncturevine.
Remarks  Controls puncturevine in snap beans where few other products are registered for use and puncturevine control is critical. Does not provide residual control of puncturevine. Tank-mixing Basagran with Raptor improves crop safety and puncturevine control. Add a nonionic surfactant or crop oil and nitrogen-based fertilizer to improve weed control.
Caution  Do not apply to drought-stressed bean plants or plants with poor root development.
Site of action  (bentazon) Group 6: photosystem II inhibitor; (imazamox) Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  (bentazon) benzothiadiazole; (imazamox) imidazolinone
•  topramezone (Impact)
Rate  0.0165 lb ai/A (0.75 oz/A)
Time  Apply postemergence to actively growing weeds 3 to 8 inches tall.
Remarks  Controls wild proso millet and many annual broadleaf weeds but does not provide residual control. Add methylated seed oil or crop oil concentrate at 1 to 1.5% v/v and UAN fertilizer or ammonium phosphate at 1.2 to 1.5% v/v to the spray solution. Spray-grade ammonium sulfate at 8.5 to 17 lb/100 gal of water may be substituted for the nitrogen fertilizers. 
Caution  Carefully read the label to determine what crops can be planted the following year.
Site of action  Group 28: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family  Triketone
probwd Quackgrass (Elytrigia repens) 
•  glyphosate
Rate  Broadcast—use 1 to 2.25 lb ae/A. Nonsodded quackgrass—use 0.75 to 1.5 lb ae/A (1 to 2 quarts). Sodded quackgrass—use 1.5 to 2.25 lb ae/A (2 to 3 quarts).
Time  Apply during fallow periods in cropping systems when quackgrass is in late boot to early flowering stage.
Remarks  Foliage must be thoroughly wet, but avoid runoff.
Caution  Glyphosate is nonselective. Retreatment may be necessary for complete control.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  EPTC (Eptam)
Rate  4 lb ai/A
Time  Apply in early spring or fall before plowing.
Remarks  This application has been promising for selective control of quackgrass in such crops as beans, potatoes, and small-seeded legumes. It does not eradicate quackgrass but does reduce growth for the season and greatly reduces amount of live roots. Before EPTC applications, soil is disked or rotated until quackgrass rhizomes are 3 to 4 inches long.
Caution  Apply to soil and immediately follow with a thorough disking in two directions to uniformly incorporate 6 inches deep.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  fluazifop (Fusilade DX)
Rate  0.25 to 0.375 lb ai/A (1 to 1.5 pints/A) for first application. If reapplication is needed, use 0.19 to 0.375 lb ai/A (0.75 to 1.5 pints/A).
Time  Apply late spring to actively growing quackgrass 6 to 10 inches tall.
Remarks  Apply with 1% v/v crop oil concentrate or 0.25% v/v nonionic surfactant. Repeat application to control established quackgrass. Acts very slowly, taking at least 2 and often 4 wk to show effects. Do not apply to stressed grasses. Do not mix with other pesticides unless recommended on label.
Caution   Do not graze treated fields.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  bromacil + diuron (Krovar I DF) 
Rate  9.6 lb ai/A (12 lb/A)
Time  Apply before weeds emerge.
Remarks  Rain is needed to activate this herbicide.
Caution  Nonselective weed control. Do not apply to areas where desirable plant roots extend.
Site of action  (bromacil) Group 5: photosystem II inhibitor; (diuron) Group 7: photosystem II inhibitor
Chemical family  (bromacil) uracil; (diuron) urea
•  dichlobenil (Casoron)
Rate  4 lb ai/A in berries; 4 to 6 lb ai/A in fruit trees and grapes
Time  Apply midwinter immediately before a cold rain to reduce volatility and enhance weed suppression. Weigh and distribute uniformly exact quantities over precisely measured areas. Oregon results over 9 yr suggest that perennial weeds can be suppressed with 4-, 3-, and 2-lb ai/A rates applied in 3 consecutive yr. Grazing livestock is prohibited. Inhibits cellulose and cell wall formation. 
Remarks  Selective in trailing berries, fruit trees, and grapes.
Site of action  Group 20: inhibits cell wall synthesis Site A
Chemical family  Nitrile
•  pronamide (Kerb)
Rate  2 to 3 lb ai/A
Time  Apply during fall or winter when soil moisture is good and more precipitation is expected. Apply before ground freezes in the cooler areas.
Remarks  Use higher application rates in heavier soil types.
Caution  A restricted-use herbicide. Follow label for crop rotations.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Benzamide
probwd Rabbitbrush (Chrysothamnus spp.) 
•  2,4-D LV ester 
Rate  3 lb ae/A
Time  Apply when rabbitbrush has 3 inches of new spring growth.
Remarks  Soil moisture should be above wilting coefficient. If Sandberg bluegrass has dried up or lost its color, soil is too dry for rabbitbrush active growth, and it is too late to spray.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ae/A
Time  Any time during the growing season.
Remarks  A selective treatment that will not damage perennial grasses at the suggested rate.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Do not use in diversified crop areas. Potatoes, beans, and most other broadleaf crops are sensitive to picloram.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Ragweed, common (Ambrosia artemisiifolia and related species) 
•  2,4-D ester
Rate  2 lb ae/A
Time  Apply after all plants have emerged but before flowering.
Remarks  Foliage must be thoroughly wet. Use 50 gal/A of water.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  glyphosate
Rate  0.75 to 1.5 lb ae/A. Make wiper application solutions with a 10 to 33% glyphosate solution. Use a 1% glyphosate solution with hand-held and high-volume equipment.
Time  Use the 0.75-lb rate when ragweed is less than 6 inches tall.
Remarks  Apply to actively growing plants.
Caution  Glyphosate controls grasses as well as other vegetation in treated areas.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  clopyralid + 2,4-D amine (Curtail) 
Rate  1 to 5 quarts/A Curtail
Time  Apply to actively growing weed after most basal leaves emerge but before bud stage.
Remarks  Lower rate for in-crop cereal grain application, higher rates for fallow, postharvest, and Conservation Reserve Program (CRP) applications. Consult label for specific directions. With CRP applications, for established grass only. For best results, wait at least 20 days after application before disturbing treated areas (cultivation, mowing, fertilization with shank-type applicators) to allow for thorough translocation. Apply in enough total spray volume to ensure good coverage.
Caution  Consult label for crop rotation restrictions before using product. Several crops may be injured up to 4 yr after application.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
probwd Ragwort, tansy (Senecio jacobaea) 
•  2,4-D or
•  picloram (Tordon) or
•  dicamba (Banvel, Rifle, or Clarity) or
•  2,4-D + dicamba (Weedmaster) or
•  triclopyr + 2,4-D (Crossbow)
Rate  1 to 2 lb ae/A 2,4-D LV ester or 2,4-D amine; or 0.25 lb ae/A picloram; or 1 lb ae/A dicamba; or 2 quarts/A Weedmaster; or 1.5 to 2 quarts/A Crossbow
Time  Apply 2,4-D in spring before any flowers appear; the earlier the application in relation to plant growth, the better the control. Picloram and dicamba can be used at the flowering stage with good results. Fall applications after rains begin seed germination have proven effective also.
Remarks  Respraying for more than 1 yr is necessary to control late-germinating seeds. Consult labels for grazing restrictions. See also pasture and rangeland section for broadcast spray.
Caution  Most picloram formulations are restricted-use herbicides. Avoid drift to sensitive crops. Do not contaminate water with picloram. Potatoes, beans, and many other broadleaf crops are sensitive to picloram. Do not use picloram in diversified cropping areas. Do not graze dairy animals within 2 wk after application.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (2,4-D) phenoxy acetic acid; (picloram and triclopyr) pyridine; (dicamba) benzoic acid 
•  aminopyralid (Milestone)
Rate  1 to 1.25 oz ae/A (4 to 5 fl oz/A Milestone)
Time  Apply to actively growing plants in the rosette.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  metsulfuron (Escort and others)
Rate  Escort—0.45 to 0.6 oz ai/A (0.75 to 1 oz/A)
Time  Apply to actively growing plants.
Remarks  Use a surfactant to increase effectiveness. Application sites differ among products; consult labels.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Rue, African (Peganum harmala) 
•  glyphosate
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  metsulfuron (Escort)
Rate  1.2 oz ai/A (2 oz/A)
Time  Apply to actively growing plants.
Remarks  Using a nonionic or silicone surfactant increases effectiveness.
Caution  Apply only to noncropland sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  imazapyr (Arsenal)
Rate  0.75 to 1 lb ae/A or as a 1% solution with methylated seed oil adjuvant
Time  Apply to actively growing foliage after plants bolt and through the fall.
Remarks  Always add the appropriate surfactant.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Rush, bog (Juncus effusus var. pacificus) 
•  2,4-D LV ester 
Rate  Use a mixture of 1.5 lb ae 2,4-D, 50 gal water, and 2 gal diesel or a nonionic surfactant for spot treatments.
Time  Apply in April or May after rush has made good spring growth.
Remarks  Foliage must be thoroughly wet.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.75 lb ae/A (1.5 pint/A)
Time  Apply any time the plants are actively growing.
Remarks  Foliage must be thoroughly wet.
Caution  Dicamba will kill clovers and other desirable broadleaf plants.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
probwd Sage, Mediterranean (Salvia aethiopis) 
Remarks  See Biological Control section in this handbook.
probwd Sagebrush, big (Artemisia tridentata) 
•  2,4-D LV ester 
Rate  2 lb ae/A
Time  Timing  is critical for effective control. Apply during active sagebrush growth in spring when Sandberg bluegrass flowers, phloxes are forming seed, and larkspur is flowering near stem top.
Remarks  Soil moisture should be above wilting coefficient. Use oil (no lower than No. 2 diesel) for aerial application. If water is used as a carrier, add a wetting agent.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  tebuthiuron (Spike 20P)
Rate  0.1 to 1 lb ai/A (1 to 5 lb/A), depending on soil type and organic matter or degree of control desired
Time  Apply in fall east of Cascades.
Remarks  Lower rates used to reduce canopy cover. Grass may be temporarily injured. May take more than 1 yr to show complete effects. No grazing restrictions.
Caution  Do not apply to frozen soil. Spike will kill trees, shrubs, and some other desirable vegetation with roots extending into treated area. Consult label for precautions.
Site of action  Group 7: photosystem II inhibitor
Chemical family  Substituted urea
probwd Sagebrush, fringed (Artemisia frigida) 
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ae/A
Time  When plants are fully emerged up to flower bud formation.
Remarks  Plants should be actively growing at the time of application. To be used on rangeland or permanent grass pastures.
Caution  Most formulations are restricted-use herbicides. Avoid drift to sensitive crops. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to these herbicides. Do not use picloram in diversified crop areas. Refer to label for grazing restrictions.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd St. Johnswort (Hypericum perforatum) 
•  2,4-D
Rate  2 lb ae/A in 50 gal of water
Time  Apply before any blossoms open, preferably on new seedlings after germination.
Remarks  Repeat applications as needed. Klamath beetles are preferred to control large infestations.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  metsulfuron (Escort and others)
Rate  Escort—0.6 oz ai/A (1 oz/A)
Time  Apply after weeds emerge.
Remarks  Use a surfactant to increase effectiveness.
Caution  Apply only to pasture, rangeland, and noncrop sites. Application sites differ among products; consult labels.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Sandbur, longspine (Cenchrus longispinus) 
•  MSMA (Bueno or Trans-Vert)
Rate  2 to 4 lb ai/A
Time  Apply after sandbur emerges.
Remarks  MSMA is more active above 70°F. Regrowth after rain or overhead irrigation may need respraying. Results are best when applied in the seedling stage.
Caution  Keep liquid or dust away from eyes. Wash eyes immediately with water if exposed.
Site of action  Group 17: not well understood
Chemical family  Organoarsenical
•  glyphosate
Rate  0.75 to 1.5 lb ae/A
Time  Apply the 0.75 rate to actively growing weeds less than 6 inches tall. If weeds are above 6 inches tall, apply 1.5 lb ae/A.
Remarks  Apply as postemergence spray to sandbur foliage.
Caution  Glyphosate is not selective in cropland.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted.
•  paraquat (Gramoxone Max)
Rate  0.38 to 0.49 lb ai/A
Time  Apply as a postemergence spray to sandbur foliage.
Remarks  Results are best if sandbur is in seedling stage. Add 8 to 16 fl oz/100 gal nonionic surfactant to spray mix. Paraquat, a contact herbicide, requires thorough spray coverage. Sandbur emerging after application will not be controlled.
Caution  A restricted-use herbicide. Do not use around homes or other areas where children or pets might come in contact with the herbicide. Do not breathe spray mist.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
•  fluazifop (Fusilade DX)
Rate  0.375 lb ai/A (1.5 pints/A), depending on site
Time  Apply to actively growing sandbur when 2 to 8 inches tall.
Remarks  See label for crops and sites. Apply with 1% (v/v) crop oil concentrate. Acts very slowly, taking at least 2 wk and often 4 wk to show effects. Do not apply to stressed grasses.
Caution  Do not use crop oil concentrate if treating sandbur in ornamentals. Do not apply if rain is expected within 1 hr.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  clethodim (Select or Arrow) 
Rate  0.9 to 0.125 lb ai/A
Time  Apply to sandbur 2 to 6 inches tall.
Remarks See label for crops and sites where clethodim may be used. If required, apply with suitable surfactant. Acts very slowly, taking at least 2 wk and often 4 wk to show effects. Do not apply to stressed grasses.
Caution  Do not apply if rain is expected within 1 hour.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  quizalofop (Assure II)
Rate  0.048 to 0.55 lb ai/A (7 to 8 fl oz/A product)
Time  Apply to sandbur 2 to 6 inches tall.
Remarks  See label for crops and sites. Include crop oil concentrate or nonionic surfactant as label recommends. Acts very slowly, taking at least 2 wk and often 4 wk to show effects. Do not apply to stressed grasses.
Caution  Do not apply if rain is expected within 1 hour.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  imazapic (Plateau)
Rate  0.063 to 0.188 lb ai/A
Time  Apply early postemergence.
Remarks  Plateau also has some preemergence activity. Add 1 quart/A methylated seed oil.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Skeletonweed, rush (Chondrilla juncea) 
•  picloram (Tordon)
Rate  1 lb ae/A
Time  Apply from late fall to early spring. For best results, apply just before or during bolting.
Remarks  Rush skeletonweed can reduce crop yields by as much as 70%, so it is important to treat small infestations. Picloram is the most effective treatment available. Retreatment is necessary.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to picloram; do not use in diversified crop areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  2,4-D or
•  MCPA
Rate  2 lb ae/A
Time  Apply to rosettes in the spring immediately before or during bolting.
Remarks  2,4-D inhibits further aboveground growth but will not prevent new plant development from root buds.
Caution  Retreatment is important.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) phenoxy acetic acid
•  clopyralid (Transline or Stinger)
Rate  0.25 to 0.375 lb ae/A (0.66 to 1 pint/A)
Time  Apply to rosette in fall or up to early bolting in spring.
Remarks  Consult labels for specific site registrations.
Caution  Product will injure or kill sensitive broadleaf forages. Consult label for crop rotation restrictions before using. Several crops may be injured several years after application.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Smartweed, dotted or perennial (Polygonum punctatum) 
•  dicamba (Banvel, Rifle, or Clarity)
Rate  2 lb ae/A
Time  Apply in March, April, May, or June.
Remarks  Foliage must be thoroughly wet.
Caution  Controls all legumes in pasture and can temporarily inhibit grass in newly established fields.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon)
Rate  1 lb ae/A
Time  March to June.
Remarks  Foliage must be thoroughly wet.
Caution  Most formulations are restricted-use herbicides. Do not graze dairy animals on treated areas within 2 wk after application. Apply rates above 0.5 lb ae/A (1 quart/A) only as a spot treatment not to exceed 25% of a landowner’s acreage in a given watershed in a single season. Avoid drift to sensitive crops. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to picloram. Do not use in diversified cropping areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Snakeweed, broom (Gutierrezia sarothrae) 
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ae/A
Time  Full leaf development to early bloom stage.
Remarks  Plants should be actively growing at time of treatment.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Beans, potatoes, and many other broadleaf crops are very sensitive to picloram. Do not use in diversified cropping areas. See label for grazing restrictions. Apply rates above 0.5 lb ae/A (1 quart/A) only as a spot treatment not to exceed 25% of a landowner’s acreage in a given watershed in one season.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  metsulfuron (Escort and others)
Rate  Escort—0.45 oz ai/A (0.75 oz/A)
Time  Apply in fall or spring.
Remarks  Application sites differ among products; consult labels.
Caution  Prevent drift to sensitive crops. Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Snapdragon, dwarf (Chaenorrhinum minus) 
Remarks  Control is unknown, although DCPA (applied before seed germinates in strawberry production) has been reported as effective. 
probwd Sorrel, red (Rumex acetosella) 
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.5 lb ae/A
Time  Apply when red sorrel has new foliage, usually November 15 to March 15. Spring application controls spring-germinating seedlings better than sprays applied earlier.
Remarks  This treatment kills red sorrel seedlings and most of the old plants. It prevents surviving plants from setting seed.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
probwd Sowthistle, perennial (Sonchus arvensis) 
•  2,4-D
Rate  2 lb ae/A
Time  Apply at bud stage and to regrowth 8 to 10 inches high.
Remarks  Repeat applications are necessary.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  clopyralid + 2,4-D amine (Curtail)
Rate  1 to 5 quarts/A Curtail
Time  Apply after most rosettes have emerged but before bud stage.
Remarks  Lower rate for in-crop cereal grain application; usually will provide only suppression. Higher rates for fallow, postharvest, and Conservation Reserve Program (CRP) applications. Consult label for specific directions. With CRP applications, for established grass only. Apply in enough total spray volume to ensure good coverage.
Caution  Consult label for crop rotation restrictions before using product. Several crops may be injured up to 4 yr after application.
Site of action  Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  aminopyralid (Milestone)
Rate  0.75 to 1.25 oz ae/A (3 to 5  fl oz/A Milestone)
Time  Apply to actively growing plants before the bud stage of growth.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Spurge, leafy (Euphorbia esula) 
Leafy spurge is a creeping perennial that emerges each year from roots that may be exceptionally deep in soil. This weed does not survive under regular cultivation. It becomes serious when it invades pastures and rangeland. Mowing is not effective and usually impractical. Sheep will graze leafy spurge enough to reduce competition with grass and to allow some production from the rangeland. Any control program, including herbicides, must be long term. Picloram or two or three applications of glyphosate seem to be a good starting point. Establishing a competitive grass and using 2,4-D to prevent seed production and to slow the growth of survivors are essential to return the land to full productivity.
•  dicamba (Banvel, Rifle, or Clarity)
Rate  4 to 8 lb ae/A
Time  Apply in spring or early summer.
Remarks  Dicamba is both soil- and foliar-active. Use on noncropland only at these application rates. Repeat each year as needed.
Caution  Do not graze livestock in treated fields within 30 days of slaughter.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon)
Rate  0.5 to 1 lb ae/A. Use higher rates in areas that are difficult to re-treat. Make a series of applications of 0.5 lb ae/A if leafy spurge is near running water or lakes.
Time  Apply any time in the growing season. Retreatments needed for several years to control seedlings.
Remarks  Picloram has given excellent control with follow-up treatments. It can persist for 2 yr at higher application rates.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to picloram. Do not use in diversified crop areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  2,4-D LV ester 
Rate  1 lb ae/A helps prevent seed formation; 6 lb ae/A helps control leafy spurge infestations.
Time  Use lower rates to prevent seed formation in the bud to early bloom stage. Use higher rates in early spring applications.
Remarks  When mowing is possible, spray 2,4-D on new regrowth 2 wk after mowing. Retreatments will be necessary.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  fosamine (Krenite S)
Rate  2 gal product/100 gal water
Time  Apply at flowering to actively growing plants. Apply spray to wet.
Remarks  Will not kill grasses and can be used next to water. Effectiveness may be reduced if rain falls on the same day.
Caution  Noncropland use only.
Site of action  Not well understood
Chemical family  Organophosphorus
•  glyphosate
Rate  0.38 to 0.75 lb ae/A
Time  Applications must be split, at 30-day intervals. For the 0.38 lb ae/A (1 pint) rate, apply 1 pint of glyphosate about June 1, July 1, and August 1. For the 0.75 lb ae/A (2 pints) rate, apply 2 pints of glyphosate about June 1 and July 1.
Remarks  Three split applications (0.38 lb ae/A each) are somewhat selective, leaving some perennial grasses. These treatments are suggested when water is near the infested area or when a reseeding of grasses is planned. Applications prevent vegetative growth the year of application and will prevent seed production the second year.
Caution  Retreatment is necessary for continued control. Glyphosate is not selective.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  glyphosate + 2,4-D (Landmaster BW)
Rate  54 oz/A Landmaster
Time  Late summer or fall.
Remarks  Apply in 3 to 10 gal of water.
Caution  Glyphosate is not selective; desirable grasses will be killed at this rate.
Site of action  (glyphosate) Group 9: inhibits EPSP synthase; (2,4-D) Group 4: synthetic auxin
Chemical family  (glyphosate) none generally accepted; (2,4-D) phenoxy acetic acid
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb ai/A
Time  Apply in late summer or fall (mid-August through October) before spurge loses its milky sap due to drought or a killing frost.
Remarks  Add 1 quart/A methylated seed oil.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Starthistle, purple (Centaurea calcitrapa) 
•  picloram (Tordon)
Rate  0.25 to 0.5 lb ae/A
Time  Apply in late spring before or during flower stem elongation.
Remarks  A selective treatment that will not damage perennial grasses at the suggested rate. Treatment made in bud stage may not prevent seed production in the year of application.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Do not use in diversified crop areas. Potatoes, beans, and most other broadleaf crops are sensitive.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  clopyralid + 2,4-D amine (Curtail)
Rate  2 to 5 quarts/A Curtail
Time  Apply after most rosettes emerge but before flower stem elongates.
Remarks  Lower rate for in-crop cereal grain application; higher rates for fallow, postharvest, and Conservation Reserve Program (CRP) applications. See label for specifics. With CRP applications, for established grass only. Apply in enough total spray volume to ensure good coverage.
Caution  Consult label for crop rotation restrictions before using Curtail. Several crops may be injured up to 4 yr after application.
Site of action  Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  clopyralid (Stinger or Transline)
Rate  0.25 to 0.5 lb ae/A
Time  Apply to starthistle rosettes but before flower stem elongates.
Remarks  Plants should be actively growing at time of treatment. Apply in 10 to 40 gal/A of water. Rain within 6 to 8 hr may reduce effectiveness.
Caution  Consult label for crop rotation restrictions before using these products. Several crops may be injured up to 4 yr after application. Avoid drift. Do not transfer livestock from treated areas to sensitive broadleaf crop areas without first grazing 7 days on untreated pasture. Follow label directions closely.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  triclopyr + clopyralid (Redeem R&P)
Rate  1.5 to 2.5 pints/A
Time  Apply from rosette to early bolt stage when starthistle is actively growing.
Remarks  Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Avoid drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  2,4-D LV ester or
•  2,4-D amine
Rate  1 to 2 lb ae/A
Time  Apply in spring when plants are still in rosettes but before flower stems elongate.
Remarks  Treat actively growing plants. Thoroughly covering foliage enhances control.
Caution  Avoid drift to sensitive crops.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) phenoxy acetic acid
•  dicamba (Banvel, Rifle, or Clarity)
Rate  1 to 2 lb ae/A
Time  Apply when plants are still in rosettes but before flower stems elongate.
Remarks  Plants should be actively growing at time of treatment.
Caution  Avoid drift to sensitive crops. Follow grazing restrictions.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
probwd Starthistle, yellow (Centaurea solstitialis) 
•  2,4-D LV ester 
Rate  1 lb ae/A in 50 gal of water
Time  Apply before flowering.
Remarks  Foliage must be thoroughly wet.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  picloram (Tordon)
Rate  0.25 to 0.375 lb ae/A
Time  In spring, to plants still in rosette through bud formation.
Remarks  A selective treatment that will not damage perennial grasses at the suggested rate. Treating at bud stage can reduce weed seed viability by 95 to 100% in the year of application.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Do not use in diversified crop areas. Potatoes, beans, and many other broadleaf crops are sensitive to picloram.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  chlorsulfuron (Telar)
Rate  1.125 oz ai/A (1.5 oz/A). Rate selection is based on weed species and soil texture.
Time  For best results apply to young, actively growing weeds.
Remarks  For suppression only. Do not apply to frozen ground. Constantly agitate while mixing in spray solution. Add 0.25% v/v nonionic surfactant to the spray mixture. Apply with ground equipment in at least 10 gal/A carrier.
Caution  See label for tank-cleaning instructions. Use on noncropland only.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  clopyralid + 2,4-D amine (Curtail) 
Rate  1 to 5 quarts/A Curtail
Time  Apply after most rosettes have emerged but before bud formation.
Remarks  Lower rate for in-crop cereal grain application, higher rates for fallow, postharvest, and Conservation Reserve Program (CRP) applications. See label for specifics. With CRP applications, for established grass only. Apply in enough total spray volume to ensure good coverage.
Caution  See label for crop rotation restrictions before Curtail. Several crops may be injured up to 4 yr after applying.
Site of action  Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  triclopyr + clopyralid (Redeem R&P)
Rate  1.5 to 2.5 pints/A
Time  Apply from rosette to early bolt stage when starthistle is actively growing.
Remarks  Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Avoid drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  clopyralid (Stinger or Transline)
Rate  0.09 to 0.375 lb ae/A (0.25 to 1 pint/A). Labeled rates vary with crops.
Time  After most rosettes have emerged but before bud formation.
Remarks  Best applied to actively growing weeds. See labels for registered sites.
Caution  See label for crop rotation restrictions before using. Several crops may be injured up to 4 yr after applying.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  aminopyralid (Milestone)
Rate  0.75 to 1.25 oz ae/A (3 to 5 fl oz/A Milestone)
Time  Apply to plants at the rosette through bolting stages.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  diflufenzopyr + dicamba (Overdrive)
Rate  0.26 to 0.35 lb ae/A (6 to 8 oz/A)
Time  Apply to seedlings or rosettes.
Remarks  Add a suitable surfactant to the spray mix.
Caution  Avoid drift to sensitive crops. Will kill legumes.
Site of action  (diflufenzopyr) Group 19: inhibits indole acetic acid transport; (dicamba) Group 4: synthetic auxin
Chemical family  (diflufenzopyr) semicarbazone; (dicamba) benzoic acid
probwd Sumpweed, poverty, or povertyweed (Iva axillaris)  
•  dicamba (Banvel, Rifle, or Clarity)
Rate  1 lb ae/A
Time  Apply when plants are actively growing.
Remarks  Adding 0.5% (v/v) surfactant enhances control.
Caution  Avoid spray drift. Avoid disturbing areas for 7 days after application.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon)
Rate  1 to 2 lb ae/A
Time  Apply during growing season when moisture will be sufficient to carry herbicide into soil. When little moisture will be available, apply in the fall.
Caution  Most formulations are restricted-use herbicides. See label for grazing restrictions. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are very sensitive to picloram. Do not use in diversified cropping areas. Apply rates above 0.5 lb ae/A (1 quart/A) only as a spot treatment not to exceed 25% of a landowner’s acreage in a watershed in a single season.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Swainsonpea or Austrian peaweed (Swainsona salsula)   
•  2,4-D LV ester 
Rate  2 lb ae/A
Time  Apply in the early bloom stage of growth.
Remarks  Retreatment may be required.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
probwd Tansy, common (Tanacetum vulgare) 
•  dicamba (Banvel, Rifle, or Clarity)  +
•  picloram (Tordon)
Rate  1 to 2 lb ae/A dicamba + 0.5 lb ae/A picloram
Time  Apply from early flower bud development to bloom stage.
Remarks  This combination is more effective than applications of the individual products.
Caution  Tordon is a restricted-use herbicide. See label for grazing restrictions. For rates above 0.5 lb ae/A (1 quart/A), apply only as a spot treatment not to exceed 25% of a landowner’s acreage in a particular watershed in a single season. Avoid drift to sensitive crops. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to these herbicides. Do not use picloram in diversified crop areas.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (dicamba) benzoic acid; (picloram) pyridine
•  metsulfuron (Escort and others)
Rate  Escort: 0.6 oz ai/A (1 oz/A)
Time  Apply to actively growing vegetation in the spring.
Remarks  Use a good surfactant at 0.25% v/v. 
Caution  Do not allow spray drift to sensitive crops. Apply only to pasture, rangeland, and noncrop sites. Application sites differ between products; consult labels.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  chlorsulfuron (Telar)
Rate  0.75 to 2.25 oz ai/A (1 to 3 oz/A)
Time  Apply to actively growing vegetation in the spring.
Remarks  Use on noncropland only.
Caution  Do not allow spray drift to sensitive crops.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
probwd Teasel, common (Dipsacus fulionum) 
•  2,4-D amine
Rate  1 lb ae/A
Time  Apply to rosette stage in fall or spring.
Remarks  Treating after teasel begins to bolt may not be effective.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  2,4-D amine  +
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.75 lb ae/A 2,4-D + 0.125 lb ae/A dicamba
Time  Apply to rosette stage in fall or spring.
Remarks  Treatments made after teasel begins to bolt may not be effective.
Caution  Avoid drift to sensitive crops.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (2,4-D) phenoxy acetic acid; (dicamba) benzoic acid
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A Telar)
Time  For best results, apply to actively growing teasel in the rosette stage.
Remarks  Constantly agitate while mixing and spraying. Add 0.25% v/v nonionic surfactant to spray mixture. Apply with ground equipment in at least 10 gal/A carrier.
Caution  Registered for use on pasture, range, Conservation Reserve Program (CRP), and noncropland only. Avoid contact with sensitive crops. Can persist in soil. Do not treat powdery, dry soils or light, sandy soils if rain is not likely soon after treatment. Do not apply to frozen ground.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  metsulfuron (Escort and others)
Rate   Escort—0.45 oz ai/A (0.75 oz/A)
Time  Apply to actively growing plants.
Remarks  Using a nonionic or silicone surfactant increases effectiveness. Application sites differ among products; consult labels.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  triclopyr + clopyralid (Redeem R&P)
Rate  1.5 pints/A
Time  Apply when actively growing.
Remarks  Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Avoid drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb ai/A
Time  Apply to rosettes.
Remarks  Add 1 quart/A methylated seed oil. 
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  diflufenzopyr + dicamba (Overdrive)
Rate  0.26 to 0.35 lb ae/A (6 to 8 oz/A)
Time  Apply to rosettes.
Remarks  Add a surfactant to the spray mix.
Caution  Avoid drift to sensitive crops. Will kill legumes.
Site of action  (diflufenzopyr) Group 19: inhibits indole acetic acid transport; (dicamba) Group 4: synthetic auxin
Chemical family  (diflufenzopyr) semicarbazone; (dicamba) benzoic acid
probwd Thistle, Canada (Cirsium arvense)—nonselective and/or noncropland control
•  chlorsulfuron (Telar)
Rate  1.125 oz ai/A (1.5 oz/A)
Time  Apply postemergence. For best results, apply to thistles in the bud-bloom stage or to fall rosettes.
Remarks  Do not apply to frozen ground. Constantly agitate while mixing in spray solution. Add 0.25% v/v nonionic surfactant to the spray mixture.
Caution  Avoid contact with sensitive crops. For noncropland use only. Chlorsulfuron can persist in soil; if land is to return to cropland, allow sufficient time for product to dissipate. Powdery, dry soils and light, sandy soils should not be treated if rain is not likely after treatment.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  dicamba (Banvel, Rifle, or Clarity)
Rate  2 lb ae/A. Spot treatment use mixtures of 2 to 4 lb ae dicamba per 100 gal of water.
Time  May be applied any time during the growing season.
Remarks  Higher rates may be required in high-rain areas. Soil residues are normally for one winter in western Oregon. Apply dicamba to growing thistles; uptake is through both foliage and root system. May mix with glyphosate to apply in fall.
Caution  Avoid drift to sensitive crops. Dicamba will damage or kill clovers in pastures.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon)
Rate  In broadcast or boom sprayers, apply 1 lb ae/A. Mixtures normally used for spot treatments include 1 lb ae per 100 gal of water.
Time  Control is best if applied to actively growing thistle after most leaves emerge but before bud stage.
Remarks  Picloram is both a foliar and soil active herbicide. It will not kill perennial grasses when used according to the label.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are very sensitive to picloram. Do not use in diversified cropping areas. Do not graze dairy animals on treated areas within 2 wk after application. For rates exceeding 0.5 lb ae/A (1 quart/A), apply only as a spot treatment not to exceed 25% of a landowner’s acreage in any particular watershed in a single season.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  glyphosate
Rate  Broadcast—1.5 to 2.25 lb ae/A; wiper—10 to 33% solution; hand-held and high-volume equipment—2% solution
Time  Apply when thistles are actively growing but past the bud growth stage. Fall applications must be before the first killing frost. Thistles that were mowed or tilled and have rosettes at least 6 inches wide in late summer or fall can be suppressed with 0.75 lb ae/A glyphosate plus 0.5 to 1% nonionic surfactant applied in 3 to 10 gal/A water.
Remarks  Wait 3 days for maximum root translocation of glyphosate before tillage.
Caution  Glyphosate controls grasses as well as other vegetation in treated areas.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  clopyralid + 2,4-D amine (Curtail)  or
•  clopyralid (Stinger or Transline)
Rate  Consult labels. Rate depends on use site.
Time  Apply to actively growing thistle after most basal leaves emerge but before bud stage.
Remarks  Lower rate for in-crop cereal grain application, higher rate for fallow, postharvest, noncrop, and Conservation Reserve Program (CRP) applications. See label for specifics. CRP applications are for established grass only. For best results, wait at least 20 days after application before disturbing treated areas (cultivation, mowing, fertilization with shank-type applicators) to allow thorough translocation. Apply in enough total spray volume to ensure good coverage.
Caution  Consult label for crop rotation restrictions before using these products. Several crops may be injured up to 4 yr after application. Do not transfer livestock from treated areas to sensitive broadleaf crop areas without first grazing 7 days on untreated pasture.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  triclopyr + clopyralid (Redeem R&P) 
Rate  2.5 to 4 pints/A
Time  Apply from rosette to bud stage to actively growing thistle.
Remarks  Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Do not allow drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  aminopyralid (Milestone)
Rate  1.25 to 1.75 oz ae/A (5 to 7 fl oz/A Milestone)
Time  Apply in the spring to plants in the prebud stage of growth or in the fall to plant regrowth.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. 
Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  diflufenzopyr + dicamba (Overdrive) 
Rate  0.26 to 0.35 lb ae/A (6 to 8 oz/A)
Time  Apply in spring to the rosettes.
Remarks  Add a surfactant, either nonionic or methylated seed oil, to the spray mix.
Caution  Avoid drift to sensitive crops. Will kill legumes.
Site of action  (diflufenzopyr) Group 19: inhibits indole acetic acid transport; (dicamba) Group 4: synthetic auxin
Chemical family  (diflufenzopyr) semicarbazone; (dicamba) benzoic acid
probwd Thistle, Canada (Cirsium arvense)—selective control in crops
•  2,4-D
selective treatment in grain and grass crops
Rate  1 to 1.5 lb ae/A
Time  Apply at the early bud stage of thistle. May require repeated applications.
Remarks  Do not apply to grass or grain crops before tiller stage or from early boot to dough stage. The 1.5-b/A rate can injure wheat.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  bentazon (Basagran)
selective in corn, dry beans, peas, and mint
Rate  0.75 to 1 lb ai/A
Time  When thistle is 6 to 8 inches tall. If needed, apply again in 10 to 14 days.
Remarks  Light leaf speckling may occur, but crop plants generally outgrow this within 10 days. Canada thistle must be thoroughly covered. Use at least 20 gal/A of water and at least 40 psi by ground. For aerial application, use at least 5 gal/A of water and a maximum of 40 psi.
Caution  Do not use near water. Avoid applying during drought or unseasonably cold weather. Expect unsatisfactory results if daytime temperatures do not reach at least 70°F during the week after applying.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Benzothiadiazole
•  clopyralid + 2,4-D amine (Curtail)
Rate  1 to 2 quarts/A Curtail. Maximum rate depends on crop.
Time  Apply 2.66 pints/A formulated product to wheat or barley after crop begins tillering and before boot stage. The 2-quart rate can be used in fallow and in grass seed crops. Canada thistle should be in the rosette to prebud growth stage.
Remarks  Apply in warm weather when weeds are actively growing and soil moisture is adequate for active plant growth.
Caution  Consult label for crop rotation restrictions before using product. Several crops may be injured up to 4 yr after application. Do not permit dairy animals or meat animals being finished for slaughter to forage or graze treated grain fields within 1 wk after treatment. Do not harvest hay from treated grain fields.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  clopyralid (Stinger)
Rate  0.09 to 0.5 lb ae/A (0.25 to 1.33 pints/A). Labeled rates vary by crop.
Time  Apply to actively growing weeds. For Canada thistle, apply after most basal leaves emerge but before bud stage.
Remarks  For most effective control, apply as a broadcast treatment to the entire infested area.
Caution  Consult label for crop rotation restrictions before using these products. Several crops may be injured up to 4 yr after application. Consult labels for registered use sites. Stinger is registered for use on field corn, sugar beets, Conservation Reserve Program (CRP), grass seed, rangeland, pasture, Christmas tree, small grains, and noncrop areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  2,4-D or
•  MCPA  +
•  dicamba (Banvel, Rifle, or Clarity)
Rate  1 lb ae/A 2,4-D or MCPA and 0.125 lb ae/A dicamba
Time  In wheat or barley, apply after crop begins tillering and before boot stage. May also be applied in stubble or fallow.
Remarks  MCPA is usually more effective on Canada thistle. Results are best if applied to actively growing thistles.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (2,4-D and MCPA) phenoxy acetic acid; (dicamba) benzoic acid 
•  chlorsulfuron (Glean)
barley, oats, wheat
Remarks  To suppress Canada thistle only. See sections in this handbook on barley, oats, and wheat for use instructions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  chlorsulfuron + metsulfuron (Finesse) 
barley and wheat
Remarks  To suppress Canada thistle only. See sections in this handbook on barley and wheat for use instructions.
Site of action  (both) Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  (both) sulfonylurea
•  dichlobenil (Casoron)
selective in trailing berries, fruit trees, grapes, and ornamentals
Rate  4 lb ai/A in berries; 4 to 6 lb ai/A in fruit trees and grapes
Time  Apply in winter or spring before active growth of crops or thistle before a rainy period to allow for activation and to avoid volatilization.
Remarks  Apply midwinter immediately before a cold rain to reduce volatility and enhance weed suppression. Weigh and distribute uniformly exact quantities over precisely measured areas. Oregon results over 9 yr suggest that perennial weeds can be suppressed with 4-, 3-, and 2-lb ai/A rates applied during 3 consecutive yr. Grazing livestock is prohibited. (Inhibits cellulose and cell wall formation.)
Site of action  Group 20: inhibits cell wall synthesis Site A
Chemical family  Nitrile
probwd Thistle, Italian (Carduus pycnocephalus)  
Thistle, slenderflower (C. tenuiflorus) 
•  MCPA amine
Rate  1.5 lb ae/A
Time  When thistle is actively growing but before bolting. Thistle rosettes wider than 6 inches may be difficult to control.
Remarks  Subclover smaller than two trifoliate leaves may be severely injured by this treatment. Other formulations may injure clover more severely. Aerial applications often produce erratic results. Results are good from applications in October through early April, but thistles may be too dormant in midwinter in some years.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  clopyralid (Transline or Stinger)
Rate  0.125 to 0.25 lb ae/A (0.33 to 0.66 pint/A)
Time  Apply to rosettes
Remarks  Consult labels for specific site registrations.
Caution  Product will injure or kill sensitive broadleaf forages. Consult label for crop rotation restrictions before using. Several crops may be injured several years after application.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
probwd Thistle, bull (Cirsium arvense) 
Thistle, milk (Silybum marianum) 
Thistle, musk (Carduus nutans) 
Thistle, Scotch (Onopordum acanthium) 
•  2,4-D
Rate  1.5 to 2 lb ae/A
Time  Spring or fall.
Remarks  Use fall treatments to control rosettes of these biennial weeds. Use spring treatments before flower stalk elongates. Annual treatments are needed to control seedlings. Pasture legumes are injured or eliminated at these rates.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  dicamba (Banvel, Rifle, or Clarity)
Rate  0.5 to 1 lb ae/A
Time  Apply before flower stalk lengthens on established plants and for seedling control. Spray fall applications to control rosettes.
Remarks  Repeat applications for several years to control new seedlings.
Caution  Dicamba residues may be in soil for 12 to 18 mo after applying. Grass tolerates dicamba at these rates.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon)
Rate  0.25 lb ae/A
Time  Apply in the fall before thistle bolts.
Remarks  Do not use on diversified cropland. Follow-up applications will be necessary to control new seedlings and escaped plants.
Caution  Most formulations are restricted-use herbicides. Soil residuals may last over 1 yr after a 0.25 lb ai/A application. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to picloram. Do not use in diversified cropping areas.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A)
Time  Apply to young, actively growing weeds.
Remarks  Do not apply to frozen ground. Maintain constant agitation while mixing product with water. Add 0.25% by volume of nonionic surfactant to spray mixture.
Caution  Avoid contact with sensitive crops. Do not treat powdery, dry soils and light, sandy soils if rain is not likely after treatment. Labeled for use on pasture, range, Conservation Reserve Program (CRP), and noncropland only.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  metsulfuron (Escort and others)
Rate  Escort: 0.6 oz ai/A (1 oz/A). 
Time  Apply postemergence to actively growing plants.
Remarks  Using a nonionic or silicone surfactant increases effectiveness. Certain biotypes of musk and Scotch thistle are more sensitive than others to metsulfuron. Application sites differ between products; consult labels.
Caution  Apply only to pasture, rangeland, and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  clopyralid + 2,4-D amine (Curtail) 
Rate  1 to 5 quarts/A Curtail
Time  Apply to actively growing thistle after most basal leaves emerge but before bud stage.
Remarks  Lower rate for in-crop cereal grain application, higher rates for fallow, postharvest, and Conservation Reserve Program (CRP) applications. Consult label for specific directions. With CRP applications, for established grass only. For best results, wait at least 20 days after application before disturbing treated areas (cultivation, mowing, fertilization with shank-type applicators) to allow thorough translocation. Apply in enough total spray volume to ensure good coverage.
Caution  See label for crop rotation restrictions before use. Several crops may be injured up to 4 yr after application.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  clopyralid (Stinger or Transline)
Rate  0.09 to 0.375 lb ae/A (0.25 to 1 pint/A). Labeled rates vary with crops.
Time  Up to the bud stage of thistles.
Remarks  Best if applied to actively growing weeds. See labels for registered sites.
Caution  Consult label for crop rotation restrictions before using these products. Several crops may be injured up to 4 yr after application.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  triclopyr + clopyralid (Redeem R&P)
Rate  1.5 to 2 pints/A
Time  Apply to actively growing thistle from rosette to early bolt stage.
Remarks  Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground.
Caution  Do not exceed 4 pints/A per year. Do not allow drift to desirable vegetation. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  aminopyralid (Milestone)
Rate  0.75 to 1.25 oz ae/A (3 to 5 fl oz/A Milestone)
Time  Apply in spring or early summer to rosettes or bolting plants or in fall to seedlings and rosettes.
Remarks  A nonionic surfactant at 1 to 2 quarts per 100 gal of spray enhances control under adverse environmental conditions.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. 
Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  glyphosate + 2,4-D (Campaign)
Rate  Broadcast—16 to 32 fl oz/A. Spot treatment—1 to 2% solution.
Time  Apply to thistles in rosette stage of growth in spring or before freeze-up in fall.
Remarks  This product is recommended for musk thistle control in rangeland, pasture, and noncroplands and for the control of those weeds listed on the product label.
Caution  Do not graze lactating dairy animals on treated grass within 7 days after application. Animals being finished for slaughter and grazing in the treated area within 30 days of treatment must be removed from the treated area 3 days before slaughter. Do not cut forage for hay within 30 days of application. No grazing restriction if product is used for spot treatments in less than 10% of the total grazed area.
Site of action  (glyphosate) Group 9: inhibits EPSP synthase; (2,4-D) Group 4: synthetic auxin
Chemical family  (glyphosate) none generally accepted; (2,4-D) phenoxy acetic acid
•  diflufenzopyr + dicamba (Overdrive)
Rate  0.175 to 0.35 lb ae/A (4 to 8 oz/A)
Time  Apply to the rosettes.
Remarks  Use higher rates on thistles that have bolted. Add a surfactant, either nonionic or methylated seed oil, to the spray mix.
Caution   Avoid drift to sensitive crops. Will kill legumes.
Site of action  (diflufenzopyr) Group 19: inhibits indole acetic acid transport; (dicamba) Group 4: synthetic auxin
Chemical family  (diflufenzopyr) semicarbazone; (dicamba) benzoic acid
probwd Toadflax, Dalmatian (Linaria dalmatica) and yellow (L. vulgaris) 
•  dicamba (Banvel, Rifle, or Clarity)
Rate  4 to 6 lb ae/A
Time  Apply in early spring before toadflax reaches bloom stage.
Remarks  Repeated applications may be necessary for complete control.
Caution  Avoid drift to sensitive crops. Dicamba severely injures or kills most broadleaf plants.
Site of action  Group 4: synthetic auxin
Chemical family  Benzoic acid
•  picloram (Tordon)
Rate  1 lb ae/A
Time  Apply to actively growing toadflax in spring before full bloom or in late summer or fall.
Remarks  A selective treatment that will not damage perennial grasses at the suggested rate.
Caution  Most formulations are restricted-use herbicides. Do not contaminate water. Do not use in diversified crop areas. Potatoes, beans, and most other broadleaf crops are sensitive to picloram. This rate for spot treatment only.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  picloram (Tordon 22K) +
•  2,4-D
Rate  0.5 lb ae/A picloram + 1.5 lb ae/A  2,4-D
Time  In spring before full bloom.
Remarks  May require annual treatment for 2 to 3 years. This rate of Tordon 22K may be broadcast.
Caution  Tordon is a restricted-use herbicide. See label for grazing restrictions. If rate exceeds 0.5 lb ae/A (1 quart/A), apply only as a spot treatment not to exceed 25% of a landowner’s acreage in any particular watershed in a single season. Avoid drift to sensitive crops. Do not contaminate water. Potatoes, beans, and many other broadleaf crops are sensitive to these herbicides. Do not use picloram in diversified crop areas.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (picloram) pyridine; (2,4-D) phenoxy acetic acid
•  chlorsulfuron (Telar)
Idaho and Washington only
Rate  1.5 to 2.25 oz ai/A (2 to 3 oz/A Telar)
Time  Apply to actively growing yellow toadflax in the bud to bloom stage.
Remarks  Suppresses yellow toadflax. Selective to grasses. Use a penetrating surfactant. Spray to wet.
Caution  Do not let spray drift onto sensitive crops. Apply only to noncropland.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  imazapic (Plateau)
Rate  0.188 lb ai/A
Time  Apply in the fall when top 25% of plant is necrotic, usually after a hard frost.
Remarks  Add 1 quart/A methylated seed oil to the spray mix.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
probwd Velvetgrass, German or creeping (Holcus mollis) 
•  EPTC (Eptam)
Rate  4 to 6 lb ai/A. Use 6-lb rate on finer soils or on heavy mats of roots and rhizomes.
Time  Apply in spring or early fall on a thoroughly prepared seedbed.
Remarks  A preplant soil-incorporated herbicide that also gives excellent results when metered into irrigation water. Effective if used in conjunction with a cropping program. Total kill requires at least 2 yr. Prevent seedlings from reestablishing the stand. Suggested crop programs are:
1.  Spray 4 to 6 lb/A in spring, and seed red clover or alfalfa on soil that has been limed and fertilized for best legume growth.
2.  Spray 2 to 3 lb/A in spring; seed to corn for 2 yr or follow with one of the other crops listed.
3.  Spray 4 to 6 lb/A in fall and seed to crimson clover or fall flax. The subsequent crop should tolerate EPTC. Re-treat the second year.
4.  Spray 4 lb/A in spring and summer fallow; follow by seeding to winter wheat or barley and treating with diuron to kill velvetgrass seedlings.
Caution  Incorporate EPTC into soil 2 to 3 inches deep immediately after application. Use sprinkler irrigation to incorporate EPTC in very dry weather.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  sethoxydim (Poast)
Rate  Up to 0.5 lb ai/A + 2 pints/A of an oil concentrate
Time  Apply in early spring when grass is growing well. Applying after April 1 may be less effective.
Remarks  Repeat applications may be needed to control well-established grass.
Caution  Do not graze treated fields.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  fluazifop (Fusilade DX)
Rate  0.25 to 0.375 lb ai/A + 1% crop oil concentrate or 0.25% nonionic surfactant
Time  Apply in early spring when grass is growing well.
Remarks  Repeat applications may be needed to control well-established grass. Do not mix with other pesticides unless label recommends.
Caution  Do not graze treated fields.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
probwd Velvetleaf (Abutilon theophrasti) 
•  2,4-D (various products)
Rate  0.25 lb ae/A
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  clomazone Command) or
•  imazethapyr (Pursuit) or
•  2,4-DB (Butyrac) or
•  glyphosate (Roundup) or
•  terbacil (Sinbar) or
•  oxyfluorfen (Goal) or
•  alachlor (Lasso) or
•  metribuzin (Sencor or Lexone) or
•  paraquat (Gramoxone Max) or
•  bromoxynil (BuctriI) or
•  norflurazon Solicam) or
•  bentazon (Basagran) or
Remarks  Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  (clomazone) Group 13: inhibits DOXP synthase; (imazethapyr) Group 2: acetolactate synthase (ALS) inhibitor; (2,4-DB) Group 4: synthetic auxin; (glyphosate) Group 9: inhibits EPSP synthase; (terbacil and metribuzin) Group 5: photosystem II inhibitor: (oxyfluorfen) Group 14: protoporphyrinogen oxidase inhibitor; (alachlor) Group 15: unknown; (paraquat) Group 22: photosystem I electron diverter; (bromoxynil and bentazon) Group 6: photosystem II inhibitor but different binding behavior than Groups 5 and 7; (norflurazon Group 12: bleaching; inhibits carotenoid biosynthesis
Chemical family  (clomazone) isoxazolidone; (imazethapyr) imidazolinone; (2,4-DB) phenoxy acetic acid; (glyphosate) none generally accepted; (terbacil) uracil; (oxyfluorfen) diphenylether; (alachlor) chloroacetamide; (metribuzin) trazine; (paraquat) bipyridilium; (bromoxynil) nitrile; (norflurazon) pyridazinone; (bentazon) benzothiadiazole
•  linuron (Lorox)
Remarks  Applied postemergence, reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action  Group 7: photosystem II inhibitor
Chemical family  Urea
probwd Waterhemlock, western (Cicuta douglasii) 
•  2,4-D or
•  MCPA
Rate  2 lb ae/A
Time  Apply at bud stage of growth.
Remarks  Plants are highly poisonous to both animals and humans.
Caution  Do not graze treated areas until plants dry up after spraying. Avoid drift to sensitive crops.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) phenoxy acetic acid
probwd Willow (Salix spp.) 
•  2,4-D LV ester 
Rate  2 to 3 lb ae/A
Time  Apply when leaves are fully developed and growing.
Remarks  Use oil (no lower than No. 2 diesel) for aerial application. Willows will resprout; therefore, retreatment may be required.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  metsulfuron (Escort)
Rate  Escort: 0.6 oz ai/A (1 oz/A)
Time  Apply to fully leafed-out brush.
Remarks  Full spray coverage is required. Use a surfactant.
Caution  Apply only to rangeland and noncrop sites.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  triclopyr amine  (Garlon 3A) or
•  triclopyr ester (Garlon 4) or
•  triclopyr + 2,4-D LV ester (Crossbow) 
Rate  Depends on which triclopyr formulation is used
Time  Apply when willows are actively growing.
Remarks  Foliage must be thoroughly wet.
Caution  Garlon products are registered for use on rights-of-way, industrial sites, and forestry (release and site preparation). Crossbow can be used on permanent pastures and rangeland up to 1.5 gal/A. Observe all grazing and harvesting restrictions. Avoid spray drift.
Site of action  (all) Group 4: synthetic auxin
Chemical family  (triclopyr) pyridine; (2,4-D) phenoxy acetic acid
probwd Woad, dyer’s (Isatis tinctoria) 
•  2,4-D LV ester 
Rate  1.9 to 2.85 lb ae/A
Time  Apply in spring or fall to rosettes, or in early summer when plant is in bud.
Remarks  For satisfactory control, it may be necessary to treat infested areas during both the rosette and bud stages of growth.
Caution  Avoid drift to sensitive crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  chlorsulfuron (Telar)
Rate  0.75 oz ai/A (1 oz/A Telar)
Time  Apply before or after weeds emerge. Results are best on young, actively growing weeds.
Remarks  Constantly agitate while mixing and spraying. Add 0.25% v/v nonionic surfactant to spray mixture. Labeled for use on pasture, range, Conservation Reserve Program (CRP), and noncropland.
Caution  Use on noncropland only. Avoid contact with sensitive crops. Can persist in soil. Do not treat powdery, dry soils or light, sandy soils if rain is not likely soon after treatment. Do not apply to frozen ground.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  metsulfuron (Escort and others)
Rate  Escort: use 0.3 to 0.6 oz ai/A (0.5 to 1 oz/A)
Time  Apply to actively growing plants.
Remarks  Use a nonionic or silicone surfactant. 
Caution  Do not let spray drift to sensitive crops. Apply only to pasture, rangeland, and noncrop sites. Application sites differ between products; consult labels.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  imazapic (Plateau)
Rate  0.125 to 0.188 lb ai/A
Time  Apply to rosettes or after blossoms open (full bloom) until plants desiccate.
Remarks  Add 1 quart/A methylated seed oil to the spray mix.
Caution  Before using, note crop rotation restrictions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone